Friday, February 15, 2008
Satellite Equipments
California Amplifier, Inc. - http://www.calamp.com/ Manufactures low noise amplifiers (LNA), low noise block down-converters (LNB) and antennas for satellite communication applications.
ViaSat, Inc. - http://www.viasat.com/ Designs, produces and markets advanced digital satellite telecommunications and wireless signal processing equipment. Features a technical library, investor information, and career opportunities.
Hughes Network Systems - http://www.hns.com/ Provides a range of global broadband, satellite, and wireless communications products for home and business.
Miteq - http://www.miteq.com/ Manufacturers of satellite communication products, components and assemblies.
Comtech EF Data Corporation - http://www.comtechefdata.com/ Manufacture a range of satellite communications products. Products include digital modems, frequency up and down converters, transceivers , amplifiers, and network management systems .
Wegener Corporation - http://www.wegener.com/ Digital video and audio equipment for the satellite broadcast industry.
ND SatCom - http://www.ndsatcom.com/ Satellite systems manufacturer operating in the Broadcast, Corporate and IP networksin the MilSat fields. Supplies a range of satellite communication components and turnkey earth stations.
Integral Systems, Inc. - http://www.integ.com/ Provides satellite ground systems, computer systems for satellite command and control, data processing, simulation, and flight software validation. (Nasdaq: ISYS).
SWE-DISH Satellite Systems - http://www.swe-dish.com/ Supplier of mobile satellite communications equipment and related services for broadband applications.
HISPASAT - http://www.hispasat.com/ Telecommunications satellite organisation from Spain.
Paradise Datacom - http://www.paradise.co.uk/ Design and manufacture high specification digital satellite communication equipment. Products include satellite modems, framing units and doppler buffer equipment.
Thrane & Thrane - http://www.thrane.com/ Supply a range of global services and products using the Inmarsat global satellite communication system. features an overview of services, news, events, a listing of distributors, and career opportunities.
Satlynx - http://www.satlynx.com/ Installation, network operations, maintenance and access to satellite transponder capacity for VSAT . Includes an information brochure in pdf format.
Able Engineering - http://www.aec-able.com/ Provides space mechanisms and satellite subsystems including coilable booms and antennas along with other special purpose mechanisms for space applications.
Satellite Engineering Group - http://www.sateng.com/ Source for products and services for customers' current needs as well as new technologies related to satellite, broadcasting and cable.
DataPath, Inc. - http://www.datapath.com/ Provides fixed earth and deployable satellite terminals, broadcast networks, VoIP with turnkey solutions, installation and training.
Techno-Sciences Inc. - http://www.technosci.com/ Provides satellite ground station equipment for the international COSPAS-SARSAT search and rescue program. Installing local user terminals and mission control centers.
Patriot Antenna Systems - http://www.sepatriot.com/ Manufacturer of the Patriot Line of Commercial Antenna Systems carrying DBS, VSAT, offset, and Prime Focus antennas.
Newtec - http://www.newtec.be/ A research and development center and manufacturer of satcom related solutions.
TriPoint Global - http://www.tripointglobal.com/ Global suppliers of satellite and wireless communications products and services, combining Prodelin, VertexRSI, CSA Wireless and Tripoint Global Broadband.
Orbit Research Ltd - http://www.orbitresearch.co.uk/ Satellite Communication Systems. Carrier monitoring equipment. Satellite earth station command and control, and remote monitoring equipment. Satellite phones.
INFOSAT Telecommunications - http://www.infosat.com/ Offer a range of products and services including terminals for individual users, and large earth stations for infrastructural projects. Includes product specifications and solutions.
Spidersat Communications - http://www.spidersat.net/ Provider of global satellite communications systems including VSAT, satellite telephones and mobile satellite internet modems.
GMPCS Personal Communications Inc. - http://www.gmpcs-us.com/ Full service provider of global mobile personal communications by satellite, via the Inmarsat, Globalstar, TMI and emerging systems. Includes a facility to purchase online, and career opportunities.
Satcom Resources - http://satcomresources.com/ Source for satellite communications equipment and services for both buyers and sellers. Includes product brochures in pdf format, pricing, and facilities to purchase online.
AAE Systems, Inc. - http://www.aaesys.com/main/ VSAT satellite turnkey systems offering satellite modems, transportable and rapid deployment equipment, and VSAT satellite applications, in MF-TDMA DAMA Mesh/Star/Hybrid networks.
TRL Electronics plc - http://www.trltech.co.uk/ Turnkey satellite earth stations, satellite modems, mobile satellite communications for military and civil applications.
Flann Microwave - http://www.flann.com/ Manufacturers of a wide range of wave-guide and related products.
GeoLink - http://www.geolink.com/ Provides worldwide satellite communication solutions.
AVL Technologies - http://www.avltech.com/ Manufacturer and supplier of mobile satellite antenna systems for SNG vehicles.
Glowlink Communications Technology, Inc - http://www.glowlink.com/ Provide hardware, software, and system expertise to help broadband satellite service providers optimize the capacity of their networks. Products include spectrum monitoring systems and link power controls.
Satellite Smart Solutions, Ltd - http://www.sat-smart.com/ Developer of wireless communication hardware for the telemetry, tracking and messaging markets. Includes information on the technology, products and applications, and related links.
Norsat International Inc. - http://www.norsat.com/ Designs, manufactures and distributes electronic products used to receive broadcast audio/video and data information from communication satellites, land broadcasting systems and fiber optics. (Nasdaq: NSATF).
Crystal Communications Inc. - http://crystalcommunications.net/ Provides telecommunications consulting and contracting services and equipment, mainly, but not limited to the cruise ship and maritime industry.
Prime Satcom Consulting Ltd - http://www.primesatcom.com/ Consultants to satellite equipment and service providers and users providing strategic sales management and project management expertise. Also design and manage satellite broadband/WiFi integration projects.
Advantech - http://www.advantech.ca/ Manufacturer of Solid State High Power Amplifiers (SSPA) and Low Noise Amplifiers (LNA) and associated redundancy equipment. Also manufactures broadband amplifiers and multiplexers.
Quake Global, Inc. - http://www.quakeglobal.com/ Designs, manufactures and markets ruggedized mobile satellite communications products for asset tracking and remote monitoring applications.
Network Innovations Inc. - http://www.networkinv.com/ Provides satellite communications products and services.
Skardin Industrial - http://www.skardin.com.tw/ Manufacturers of satellite receivers, video sender, audio senders and IR extenders.
Iterative Connections - http://www.iterativeconnections.com/ Satellite communications modem manufacturer.
TISC - http://www.tiscsat.com/ Specialising in Inmarsat, VSAT, WebSat and Micro GSM systems. TISC is an Inmarsat and Eutelsat Service Provider.
SatCom Distribution - http://www.satcomgroup.com/ Provider of satellite communications equipment for mobile, portable, fixed, maritime and aeronautical use.
Novra Technologies Inc. - http://www.novra.com/ Develops broadband receivers, transceivers, and gateways for satellite, terrestrial wireless and cable applications. Includes product specifications, investor information, and career opportunities.
Sematron (UK) Ltd - http://www.sematron.com/ A specialist distributor of RF and Microwave Components, instrumentation, Satellite Communications ground station equipment and Time and Frequency instrument and systems.
Latitude Technologies Corporation - http://www.latitudetech.com/ Data and messaging systems to complement satellite phone systems with remote operation and aviation applications.
Swedish Microwave AB - http://www.smw.se/ Manufacturer of microwave and RF components for satellite receiving equipment. LNAs, LNBs, frequency converters, waveguide components.
Videocom 2000 - http://www.videocom-2000.com/ Provides satellite telecommunication solutions, digital, television, video broadcasting, video surveillance. Located in France with service throughout Europe.
IDG Europe AB - http://www.idgeurope.com/ Suppliers of satellite communications systems and portable power supplies.
Wright Technologies Limited - http://wrights.co.nz/ Rents, sells and services satellite telephones for use by business, not for profit, government and defence organisations. Also services marine electronic equipment.
Advanced Switch Technology - http://www.astswitch.com/ Manufactures Microwave waveguide, Dual and Coaxial Switches for the telecommication Industry.
Iridium Phones and Accessories - http://www.satwest.com/ SatWest provides satellite phones, pagers, data transfer equipment, and satellite accessories.
Telsat Communications Ltd - http://www.telsat.com Global importers and exporters of quality satellite TVRO hardware. Located in New Zealand.
Applied Instruments, Inc. - http://www.appliedin.com/ Manufacturer of test equipment for the telecommunications industry, include CATV and satellite meters, finders, RF signal generators and noise power ratio test sets.
Vocality International Ltd - http://www.vocality.com Provides multiplexers and satellite simulators for mobile satellite users.
Creacomm - http://www.creacomm.com/ Designs and manufactures hardware for mobile data communication industry solutions.
Satellite Communication Center - http://www.sccenter.ru/eng/index.html Manufacturer and systems integrator of C and Ku band satellite earth stations. Located in Moscow.
Sintel Satellite Services Inc. - http://www.sintelsat.com/ Provides satcom project engineering, system integration, on-site project implementation, and program management services .
Sotca Inc. - http://www.sotca.com/ Designs and manufactures synthesized frequency converters for satellite communications, low noise amplifiers and custom products.
Horizon Satellite Services - http://www.horizon-satellite.com/ Provides satellite services in the Middle East, Asia and Africa.
Sat-Comm - http://www.sat-comm.com/ Specialist builders of satellite newsgathering and television production vehicles for the broadcast industry. Product details and contact information.
Delta Communication Ltd. - http://www.deltacomm.co.uk/ Satellite communication consultancy and software engineering products. Site also contains some useful java satellite communication calculation tools.
Glocom Corporation - http://www.glocom-us.com/ Manufacture user terminals, gateway channel cards, and test equipment for satellite mobile communications and digital networking services. Features product specifications and a resellers listing.
Novella Satcoms - http://www.novella.co.uk/ Manufacturers of satellite communication products including frequency up and down converters, tracking receivers, test translators and uplink power control systems.
Satellite Systems Corp. - http://www.satsyscorp.com/ Manufactures satellite beacon receivers, frequency conversion products, FM SCPC modulators and demodulators, transverters, and block converters and redundant switching systems for satellite earth stations. Also provides satellite earth station installation and integration.
Svs Telekom - http://www.svstelekom.com.tr Offers turnkey solutions, engineering, designs, maintenance and consultation on all types of satellite communication systems. [May not work in all browsers]
NRoute Communications, Inc. - http://www.nroute.net/ Markets a proprietary mobile, high-speed wireless network that delivers full video, audio and Internet access via wireless and satellite technologies to passengers on trains and motor coaches.
American Antenna - http://www.americanantenna.com/ A manufacturer, distributor, and installer of commercial earth station antennas and related equipment for the broadcast and cable industry.
AimSat - http://www.aimsat.com/ Manufacturer of composite satellite dishes for satellite television systems.
Optimal Satcom, Inc - http://www.optimalsatcom.com Provider of software for satellite operators and satellite capacity users. Software products include COMPLAN and COMSAT STAR to enable optimal use of satellite capacity.
SatService GmbH - http://satservicegmbh.de/ Offer a range of services and systems for satellite earth stations. Features a completed project portfolio with technical data and specifications.
SDI- Swiden Distributing Inc . - http://www.swidendist.com/ Offers a selection of satellite dish systems and related equipment and accessories.
MobileSat Communications Inc. - http://www.mobilesat.ca/ Provides secure high-speed internet, multiple phone and fax lines to remote locations.
Greatdvb Digital Technology - http://www.greatdvb.com/ Manufacturer of satellite and cable receivers, GPS systems, and related equipment. China.
Quintech Electronics - http://www.quintechelectronics.com/ Designs and manufactures RF signal management solutions for Satellite, Cable, Broadcast and other telecommunications networks.
RTI Products - http://rti-products.com/ Manufactures electronic snow sensing and anti-icing systems for telecommunications industry.
L.TEQ Limited - http://www.lteq.com/ Supplies a range of satellite products including main earth station equipment, and point to point wireless systems.
BT Satellite Services - http://www.satellite.bt.com/ Provide a range of satellite management and engineering services. Includes a range of information on global services, technical data, and case studies.
Spirit Wireless - http://www.spiritwireless.com/ Satellite phones, Portable Docking Kit, sales and rentals for mobile, marine and data applications.
Global Professional - http://www.globalprofessional.co.uk/ Manufacture and custom construction of satellite, GPS and VSAT equipment for the professional user market.
SatService GmbH - http://www.satnms.com/ Provides solutions for satellite ground stations and communication systems including antenna control, monitoring, and network management systems.
Satphone UK - http://www.satphone.co.uk/ Supplier of satellite telephones and airtime including Iridium, Thuraya, Inmarsat and Globalstar
Atlantic Satellite Corporation - http://atlanticsat.com/ Designs and manufactures satellite beacon tracking receivers,up and down converters, redundant switches and handheld test equipment.
Global Satcom Technology, Inc. - http://www.globalsatcom.com/ Design, manufacture and install transportable satellite communications systems. Includes product specifications and photographs.
DigiVision Satellite Services - http://www.installs.com/ Installer of satellite dishes, wireless internet devices and home theatre.
Coolsat Canada - http://www.coolsatcanada.com/ Canadian wholesale distributor of Coolsat satellite FTA receivers.
Castell Satcom Radio - http://www.castellsatcomradio.com/ Supplier of satellite phone, radio equipment and services to organizations working in remote and hazardous areas.
Apna DTH - http://www.apnadth.com/ Terminals and designed platforms consisting of a variety of parabolic dish fed terminals with LNBF and set-top boxes to suit needs of Indian customers.
Datek Pty Ltd - http://www.datek.net.au/ Supplies and installs satellite dishes from 65cm up to 3.1m in domestic and commercial situations.
Astrotel Europe - http://www.astroteleurope.com/ Supply products in C, KU, S and the new KA band frequencies for both the TVRO and professional satellite markets. Products include lnb's, lnbf's, and feedhorns.
CcS Satcom - http://www.ccs-satcom.co.uk/ Supplier of RF matrix switches, splitters, frequency converters and directional couplers for frequencies from 5MHz to 14GHz. Also supply GSM modems and terminals.
Micro Phase Communications - http://www.microphaseinc.com/ Manufacturer of frequency converters and audio modulators and demodulators for satellite communications.
Genix Electronics Inc - http://www.genix.co.kr/ Develops satellite/terrestial broadcasting reception devices and accessories.
Skynet Mobile Communications - http://www.skynetmobile.com.au/ Supplies satellite navigation and asset tracking equipment, computer hardware and software.
S3 Satcom Ltd. - http://www.sthreesatcom.plus.com/ Supplies and installs fixed earth station uplink systems for TV contribution and distribution, internet backbone connections and VSAT networks for broadcasters and telecom operators worldwide.
GbSAT - http://www.gbsat.com/ Manufacture of satellite receivers with DiSEqC 1.2 and USALS 2CI, PVR machines, embedded Irdeto, and receivers with a traditional positioner.
Ace China International Enterprise Ltd. - http://www.dvb-device.com/ Chinese manufacturer and exporter of digital video broadcasting equipment.
Smartdish Inc. - http://smartdish.net/ Specializes in the manufacture of automatic satellite uplink mounts for remote applications.
Prism IP Solutions - http://www.prismip.com/ Provides connectivity and interconnection solutions across terrestrial, radio and satellite technologies
AAVAC Communications - http://www.aavac-communications.co.uk/ Provides broadcast, satellite radio distribution systems and wireless networks consulting.
Carrick Communications - http://www.carrickcom.com/ A consultancy and management company with a wide range of experience in the field.
DCA Systems, Inc. - http://www.dcasystems.com/ Telecommunication systems consultants offering satellite equipment and bandwidth planning services.
Global NetworX - http://www.globalnetworx.com/ Manufacturers representative for satellite tranceivers and digital video compression products . Includes product data and specification sheets
Quanzhou Licheng Feijie Radio Factory - http://www.feijie-sat.com/ manufacturer of digital satellite receiver, DVB receiver, cable receiver, CATV accessories and satellite accessories.
Finninger and Helbach - http://www.digitalsatellitefrance.com/ Provides satellite television receivers and installation services.
Amersham Aerial Fix - http://www.bucks-berks-herts-aerials.co.uk/ Aerial and satellite installation for domestic and commercial clients in Bucks, Berkshire and Hertfordshire.
EagleSat - http://www.eaglesat.net/ Specializing in remote communications, providing secure, reliable remote communications, VoIP, Internet, data and Wi-Fi for business needs.
Mid-State Distributing - http://www.m-state.com/ Supplier of satellite systems, off air antennas, audio/video and home theater products.
Delta Wave Communications Inc. - http://www.deltawavecomm.com/ Offer a range of services and products for terrestial and marine applications for worldwide mobile satellite communications. Includes downloadable pricing schedules, and equipment brochures.
Crown-sat - http://www.crown-sat.com/ Manufacturer of digital satellite receivers and accessories. Chin
Satellite Maniacs - http://www.satmaniacs.com/ Wholesale distributor of satellite FTA receivers.
Yojia Technology - http://www.yojiatech.com Manufacture of digital satellite receiver. China.
Thursday, February 14, 2008
Tuesday, February 12, 2008
UNPACKING & ASSEMBLING THE DISH
STEP 6 -- UNPACKING & ASSEMBLING THE DISH
IMPORTANT NOTE: Parabolic antenna dishes may vary from one manufacturer to another. The guidelines which follow apply to most types of dishes. Please adapt and apply these principles to the dish you are using. Follow the manufacturer’s instructions closely, making at least 1 photocopy for your records. If you do not have a copy of the manufacturer’s instructions, ask ATN for a more detailed version of this Step, which includes photos.
If you are not going to install the dish immediately, carry out this step anyhow, to ensure that you have all the parts of the dish. Especially if parcels have been damaged, missing parts need to be traced as soon as possible.
6.1 Unpack the parts.
Find a flat, clean surface to unpack the parts. Carefully unpack the parts, grouping similar ones together. Take care not to bend or damage any parts during unpacking. Keep shipping papers and documents for 3 months. Keep the instructions permanently in a plastic bag or suitable folder.
Picture 7
Two sections of adjacent mesh6.2 Check to ensure that all parts have arrived
Use the list of parts supplied by the manufacturer.
Start at the top of the list and check (tick/mark) against each line.
If some parts have not arrived, immediately contact whoever delivered the parcels to locate missing parts.
Take the packet of nuts & bolts and sort into piles of the same type.
Put each type into separate packets or plastic bags.
If you will not assemble the dish the same day, keep especially the smaller parts, such as the Feedhorn /LNB in a secure place.
6.3 Assemble the dish
Read the manufacturer’s instructions at least twice, noting whether you will need any special tools or assistance.
If you want to have good reception and clear pictures, the dish antenna must be carefully assembled to ensure a precise parabolic shape. Any distortion or twisting of the shape will reduce the effectiveness of your reception. Take care not to bend or damage any parts during assembly.
Important: During assembly tighten the bolts and nuts loosely with fingers only to save time in the final stages.
Assemble the dish antenna, in the following order:
Stage 1 ASSEMBLE THE FRAMEWORK
Stage 2 ATTACH THE MESH
Note: Be sure the mesh is consistent all the way around the dish - there may be a reflective coating or a distinctive weave / pattern
Important: The mesh is attached to the frame with plastic buttons (or hooks / screws), some of which can be used ONCE only . To remove a button, it would need to be cut off, and could not be used again.
Great care needs to be taken to insert a button only when the mesh is in the correct position. In cases where the buttons pop out, they may be replaced at regular intervals with self-tapping screws (with small heads) or possible small bolts.
TIP: In high wind areas, place beads or strips of silicone glue on the ribs before attaching the mesh.
Check that each section or the rim or edge is the same distance from the flat surface, then tighten all the bolts and nuts. (Important: DO NOT OVERTIGHTEN BOLTS, as this could cause the dish to be distorted or the threads of the nuts or bolts to be damaged.
Check the shape
After assembly, turn the dish to face upwards and carefully “sight” all the way around, along the rim, (with your eye at the level of both the near and far rim) to check that the rim is straight. If not, the dish is warped and needs correction by loosening the bolts and re-setting.
TIP: Tape two pieces of string from one rim to the opposite rim at right angles to each other. These strings should touch very lightly. If the strings are separated where they meet, or too tightly together, the dish rim is not in line and the shape is not correct.
Stage 3 ATTACH THE POLE MOUNT
Stage 4 ASSEMBLE AND MOUNT THE LNB TRIPOD
TIP: In hail areas, protect the face of the dish with shade cloth (30 - 40% screen).
Stage 5 MOUNT THE LNB ON THE TRIPOD
1) The feedhorn / LNB must be centred on the dish. This may be done by carefully measuring from the rim to the throat of the feedhorn from 4 different sides and adjusting the feedhorn until all measurements are identical.
Another way would be use two pieces of string as in Section 6.3. Ensure that they touch lightly exactly in the centre of the dish. The point at which they cross should be the centre, which should be visible in the centre when looking at them through the feedhorn.
2) Mount the LNB in the Scalar Ring. See Picture 20.
Picture 20
Positioning Feedhorn
in Scalar Ring
6.4 LNB Setting
At this stage, there are two critical settings on the LNB. It is easier make these settings now, but they could be done after the dish has been mounted on the pole, together with the settings described in Section 7.4
These settings are:
1) f/ D ratio (precise distance or focal length from centre of dish),
2) Offset of the LNB (degree of rotation),
Setting No 1 (The focal length)
The focal length is the distance from the deepest point in the center of the dish to the front of the feedhorn on the LNB. On the Acer LNB this is 30mm inside. Others may vary. To start with, look for the markings on the side of the LNB and set the focal length in the middle of these markings. You can fine tune later.
For technical specialists: Refer to the instructions for your dish to obtain the correct focal length. If you do not have the instructions, you may need to use the formula below, where D = diameter of dish, d=depth of dish (measured in the center from the face to deepest point). Use a piece of string drawn tightly across the center of the face from one rim to the opposite rim to get an accurate face position. The focal length is = f
The formula is: f = D x D / 16 x d.
Example: D = 2.3m and d = 0.375m. f = 2.3 x 2.3 / 16 x 0.375 = 5.29/6 = 0.882m
Setting No 2 (The degree of rotation or polarization offset)
NB: On polar mount dishes, the 0 - 180° line should be parallel to the polar axis.
On fixed dishes, the polarization offset needs to be set on the LNB, which
is usually marked on the top with settings of 10, 20 30 and more degrees. See Picture 21. This should be measured assuming 0 degrees is at the 12 O’clock position (pointing straight up).
Hemisphere
Offset degrees
Rotate LNB*
Southern
Positive
Anti-clockwise
Northern
Negative
Clockwise
* When viewed from rear of LNB (as per Picture 21)
Example: For Johannesburg 53° offset requires the LNB to be rotated
anti-clockwise (to the left) by 53°
Picture 21
Side/rear view of Acer LNB
showing offset degrees
on the rear.
STEP 6 -- UNPACKING & ASSEMBLING THE DISH
IMPORTANT NOTE: Parabolic antenna dishes may vary from one manufacturer to another. The guidelines which follow apply to most types of dishes. Please adapt and apply these principles to the dish you are using. Follow the manufacturer’s instructions closely, making at least 1 photocopy for your records. If you do not have a copy of the manufacturer’s instructions, ask ATN for a more detailed version of this Step, which includes photos.
If you are not going to install the dish immediately, carry out this step anyhow, to ensure that you have all the parts of the dish. Especially if parcels have been damaged, missing parts need to be traced as soon as possible.
6.1 Unpack the parts.
Find a flat, clean surface to unpack the parts. Carefully unpack the parts, grouping similar ones together. Take care not to bend or damage any parts during unpacking. Keep shipping papers and documents for 3 months. Keep the instructions permanently in a plastic bag or suitable folder.
UNPACKING & ASSEMBLING THE DISH
Picture 7
Two sections of adjacent mesh6.2 Check to ensure that all parts have arrived
Use the list of parts supplied by the manufacturer.
Start at the top of the list and check (tick/mark) against each line.
If some parts have not arrived, immediately contact whoever delivered the parcels to locate missing parts.
Take the packet of nuts & bolts and sort into piles of the same type.
Put each type into separate packets or plastic bags.
If you will not assemble the dish the same day, keep especially the smaller parts, such as the Feedhorn /LNB in a secure place.
6.3 Assemble the dish
Read the manufacturer’s instructions at least twice, noting whether you will need any special tools or assistance.
If you want to have good reception and clear pictures, the dish antenna must be carefully assembled to ensure a precise parabolic shape. Any distortion or twisting of the shape will reduce the effectiveness of your reception. Take care not to bend or damage any parts during assembly.
Important: During assembly tighten the bolts and nuts loosely with fingers only to save time in the final stages.
Assemble the dish antenna, in the following order:
Stage 1 ASSEMBLE THE FRAMEWORK
Stage 2 ATTACH THE MESH
Note: Be sure the mesh is consistent all the way around the dish - there may be a reflective coating or a distinctive weave / pattern
Important: The mesh is attached to the frame with plastic buttons (or hooks / screws), some of which can be used ONCE only . To remove a button, it would need to be cut off, and could not be used again.
Great care needs to be taken to insert a button only when the mesh is in the correct position. In cases where the buttons pop out, they may be replaced at regular intervals with self-tapping screws (with small heads) or possible small bolts.
TIP: In high wind areas, place beads or strips of silicone glue on the ribs before attaching the mesh.
Check that each section or the rim or edge is the same distance from the flat surface, then tighten all the bolts and nuts. (Important: DO NOT OVERTIGHTEN BOLTS, as this could cause the dish to be distorted or the threads of the nuts or bolts to be damaged.
Check the shape
After assembly, turn the dish to face upwards and carefully “sight” all the way around, along the rim, (with your eye at the level of both the near and far rim) to check that the rim is straight. If not, the dish is warped and needs correction by loosening the bolts and re-setting.
TIP: Tape two pieces of string from one rim to the opposite rim at right angles to each other. These strings should touch very lightly. If the strings are separated where they meet, or too tightly together, the dish rim is not in line and the shape is not correct.
Stage 3 ATTACH THE POLE MOUNT
Stage 4 ASSEMBLE AND MOUNT THE LNB TRIPOD
TIP: In hail areas, protect the face of the dish with shade cloth (30 - 40% screen).
Stage 5 MOUNT THE LNB ON THE TRIPOD
1) The feedhorn / LNB must be centred on the dish. This may be done by carefully measuring from the rim to the throat of the feedhorn from 4 different sides and adjusting the feedhorn until all measurements are identical.
Another way would be use two pieces of string as in Section 6.3. Ensure that they touch lightly exactly in the centre of the dish. The point at which they cross should be the centre, which should be visible in the centre when looking at them through the feedhorn.
2) Mount the LNB in the Scalar Ring. See Picture 20.
Picture 20
Positioning Feedhorn
in Scalar Ring
6.4 LNB Setting
At this stage, there are two critical settings on the LNB. It is easier make these settings now, but they could be done after the dish has been mounted on the pole, together with the settings described in Section 7.4
These settings are:
1) f/ D ratio (precise distance or focal length from centre of dish),
2) Offset of the LNB (degree of rotation),
Setting No 1 (The focal length)
The focal length is the distance from the deepest point in the center of the dish to the front of the feedhorn on the LNB. On the Acer LNB this is 30mm inside. Others may vary. To start with, look for the markings on the side of the LNB and set the focal length in the middle of these markings. You can fine tune later.
For technical specialists: Refer to the instructions for your dish to obtain the correct focal length. If you do not have the instructions, you may need to use the formula below, where D = diameter of dish, d=depth of dish (measured in the center from the face to deepest point). Use a piece of string drawn tightly across the center of the face from one rim to the opposite rim to get an accurate face position. The focal length is = f
The formula is: f = D x D / 16 x d.
Example: D = 2.3m and d = 0.375m. f = 2.3 x 2.3 / 16 x 0.375 = 5.29/6 = 0.882m
Setting No 2 (The degree of rotation or polarization offset)
NB: On polar mount dishes, the 0 - 180° line should be parallel to the polar axis.
On fixed dishes, the polarization offset needs to be set on the LNB, which
is usually marked on the top with settings of 10, 20 30 and more degrees. See Picture 21. This should be measured assuming 0 degrees is at the 12 O’clock position (pointing straight up).
Hemisphere
Offset degrees
Rotate LNB*
Southern
Positive
Anti-clockwise
Northern
Negative
Clockwise
* When viewed from rear of LNB (as per Picture 21)
Example: For Johannesburg 53° offset requires the LNB to be rotated
anti-clockwise (to the left) by 53°
Picture 21
Side/rear view of Acer LNB
showing offset degrees
on the rear.
IMPORTANT NOTE: Parabolic antenna dishes may vary from one manufacturer to another. The guidelines which follow apply to most types of dishes. Please adapt and apply these principles to the dish you are using. Follow the manufacturer’s instructions closely, making at least 1 photocopy for your records. If you do not have a copy of the manufacturer’s instructions, ask ATN for a more detailed version of this Step, which includes photos.
If you are not going to install the dish immediately, carry out this step anyhow, to ensure that you have all the parts of the dish. Especially if parcels have been damaged, missing parts need to be traced as soon as possible.
6.1 Unpack the parts.
Find a flat, clean surface to unpack the parts. Carefully unpack the parts, grouping similar ones together. Take care not to bend or damage any parts during unpacking. Keep shipping papers and documents for 3 months. Keep the instructions permanently in a plastic bag or suitable folder.
Picture 7
Two sections of adjacent mesh6.2 Check to ensure that all parts have arrived
Use the list of parts supplied by the manufacturer.
Start at the top of the list and check (tick/mark) against each line.
If some parts have not arrived, immediately contact whoever delivered the parcels to locate missing parts.
Take the packet of nuts & bolts and sort into piles of the same type.
Put each type into separate packets or plastic bags.
If you will not assemble the dish the same day, keep especially the smaller parts, such as the Feedhorn /LNB in a secure place.
6.3 Assemble the dish
Read the manufacturer’s instructions at least twice, noting whether you will need any special tools or assistance.
If you want to have good reception and clear pictures, the dish antenna must be carefully assembled to ensure a precise parabolic shape. Any distortion or twisting of the shape will reduce the effectiveness of your reception. Take care not to bend or damage any parts during assembly.
Important: During assembly tighten the bolts and nuts loosely with fingers only to save time in the final stages.
Assemble the dish antenna, in the following order:
Stage 1 ASSEMBLE THE FRAMEWORK
Stage 2 ATTACH THE MESH
Note: Be sure the mesh is consistent all the way around the dish - there may be a reflective coating or a distinctive weave / pattern
Important: The mesh is attached to the frame with plastic buttons (or hooks / screws), some of which can be used ONCE only . To remove a button, it would need to be cut off, and could not be used again.
Great care needs to be taken to insert a button only when the mesh is in the correct position. In cases where the buttons pop out, they may be replaced at regular intervals with self-tapping screws (with small heads) or possible small bolts.
TIP: In high wind areas, place beads or strips of silicone glue on the ribs before attaching the mesh.
Check that each section or the rim or edge is the same distance from the flat surface, then tighten all the bolts and nuts. (Important: DO NOT OVERTIGHTEN BOLTS, as this could cause the dish to be distorted or the threads of the nuts or bolts to be damaged.
Check the shape
After assembly, turn the dish to face upwards and carefully “sight” all the way around, along the rim, (with your eye at the level of both the near and far rim) to check that the rim is straight. If not, the dish is warped and needs correction by loosening the bolts and re-setting.
TIP: Tape two pieces of string from one rim to the opposite rim at right angles to each other. These strings should touch very lightly. If the strings are separated where they meet, or too tightly together, the dish rim is not in line and the shape is not correct.
Stage 3 ATTACH THE POLE MOUNT
Stage 4 ASSEMBLE AND MOUNT THE LNB TRIPOD
TIP: In hail areas, protect the face of the dish with shade cloth (30 - 40% screen).
Stage 5 MOUNT THE LNB ON THE TRIPOD
1) The feedhorn / LNB must be centred on the dish. This may be done by carefully measuring from the rim to the throat of the feedhorn from 4 different sides and adjusting the feedhorn until all measurements are identical.
Another way would be use two pieces of string as in Section 6.3. Ensure that they touch lightly exactly in the centre of the dish. The point at which they cross should be the centre, which should be visible in the centre when looking at them through the feedhorn.
2) Mount the LNB in the Scalar Ring. See Picture 20.
Picture 20
Positioning Feedhorn
in Scalar Ring
6.4 LNB Setting
At this stage, there are two critical settings on the LNB. It is easier make these settings now, but they could be done after the dish has been mounted on the pole, together with the settings described in Section 7.4
These settings are:
1) f/ D ratio (precise distance or focal length from centre of dish),
2) Offset of the LNB (degree of rotation),
Setting No 1 (The focal length)
The focal length is the distance from the deepest point in the center of the dish to the front of the feedhorn on the LNB. On the Acer LNB this is 30mm inside. Others may vary. To start with, look for the markings on the side of the LNB and set the focal length in the middle of these markings. You can fine tune later.
For technical specialists: Refer to the instructions for your dish to obtain the correct focal length. If you do not have the instructions, you may need to use the formula below, where D = diameter of dish, d=depth of dish (measured in the center from the face to deepest point). Use a piece of string drawn tightly across the center of the face from one rim to the opposite rim to get an accurate face position. The focal length is = f
The formula is: f = D x D / 16 x d.
Example: D = 2.3m and d = 0.375m. f = 2.3 x 2.3 / 16 x 0.375 = 5.29/6 = 0.882m
Setting No 2 (The degree of rotation or polarization offset)
NB: On polar mount dishes, the 0 - 180° line should be parallel to the polar axis.
On fixed dishes, the polarization offset needs to be set on the LNB, which
is usually marked on the top with settings of 10, 20 30 and more degrees. See Picture 21. This should be measured assuming 0 degrees is at the 12 O’clock position (pointing straight up).
Hemisphere
Offset degrees
Rotate LNB*
Southern
Positive
Anti-clockwise
Northern
Negative
Clockwise
* When viewed from rear of LNB (as per Picture 21)
Example: For Johannesburg 53° offset requires the LNB to be rotated
anti-clockwise (to the left) by 53°
Picture 21
Side/rear view of Acer LNB
showing offset degrees
on the rear.
STEP 6 -- UNPACKING & ASSEMBLING THE DISH
IMPORTANT NOTE: Parabolic antenna dishes may vary from one manufacturer to another. The guidelines which follow apply to most types of dishes. Please adapt and apply these principles to the dish you are using. Follow the manufacturer’s instructions closely, making at least 1 photocopy for your records. If you do not have a copy of the manufacturer’s instructions, ask ATN for a more detailed version of this Step, which includes photos.
If you are not going to install the dish immediately, carry out this step anyhow, to ensure that you have all the parts of the dish. Especially if parcels have been damaged, missing parts need to be traced as soon as possible.
6.1 Unpack the parts.
Find a flat, clean surface to unpack the parts. Carefully unpack the parts, grouping similar ones together. Take care not to bend or damage any parts during unpacking. Keep shipping papers and documents for 3 months. Keep the instructions permanently in a plastic bag or suitable folder.
UNPACKING & ASSEMBLING THE DISH
Picture 7
Two sections of adjacent mesh6.2 Check to ensure that all parts have arrived
Use the list of parts supplied by the manufacturer.
Start at the top of the list and check (tick/mark) against each line.
If some parts have not arrived, immediately contact whoever delivered the parcels to locate missing parts.
Take the packet of nuts & bolts and sort into piles of the same type.
Put each type into separate packets or plastic bags.
If you will not assemble the dish the same day, keep especially the smaller parts, such as the Feedhorn /LNB in a secure place.
6.3 Assemble the dish
Read the manufacturer’s instructions at least twice, noting whether you will need any special tools or assistance.
If you want to have good reception and clear pictures, the dish antenna must be carefully assembled to ensure a precise parabolic shape. Any distortion or twisting of the shape will reduce the effectiveness of your reception. Take care not to bend or damage any parts during assembly.
Important: During assembly tighten the bolts and nuts loosely with fingers only to save time in the final stages.
Assemble the dish antenna, in the following order:
Stage 1 ASSEMBLE THE FRAMEWORK
Stage 2 ATTACH THE MESH
Note: Be sure the mesh is consistent all the way around the dish - there may be a reflective coating or a distinctive weave / pattern
Important: The mesh is attached to the frame with plastic buttons (or hooks / screws), some of which can be used ONCE only . To remove a button, it would need to be cut off, and could not be used again.
Great care needs to be taken to insert a button only when the mesh is in the correct position. In cases where the buttons pop out, they may be replaced at regular intervals with self-tapping screws (with small heads) or possible small bolts.
TIP: In high wind areas, place beads or strips of silicone glue on the ribs before attaching the mesh.
Check that each section or the rim or edge is the same distance from the flat surface, then tighten all the bolts and nuts. (Important: DO NOT OVERTIGHTEN BOLTS, as this could cause the dish to be distorted or the threads of the nuts or bolts to be damaged.
Check the shape
After assembly, turn the dish to face upwards and carefully “sight” all the way around, along the rim, (with your eye at the level of both the near and far rim) to check that the rim is straight. If not, the dish is warped and needs correction by loosening the bolts and re-setting.
TIP: Tape two pieces of string from one rim to the opposite rim at right angles to each other. These strings should touch very lightly. If the strings are separated where they meet, or too tightly together, the dish rim is not in line and the shape is not correct.
Stage 3 ATTACH THE POLE MOUNT
Stage 4 ASSEMBLE AND MOUNT THE LNB TRIPOD
TIP: In hail areas, protect the face of the dish with shade cloth (30 - 40% screen).
Stage 5 MOUNT THE LNB ON THE TRIPOD
1) The feedhorn / LNB must be centred on the dish. This may be done by carefully measuring from the rim to the throat of the feedhorn from 4 different sides and adjusting the feedhorn until all measurements are identical.
Another way would be use two pieces of string as in Section 6.3. Ensure that they touch lightly exactly in the centre of the dish. The point at which they cross should be the centre, which should be visible in the centre when looking at them through the feedhorn.
2) Mount the LNB in the Scalar Ring. See Picture 20.
Picture 20
Positioning Feedhorn
in Scalar Ring
6.4 LNB Setting
At this stage, there are two critical settings on the LNB. It is easier make these settings now, but they could be done after the dish has been mounted on the pole, together with the settings described in Section 7.4
These settings are:
1) f/ D ratio (precise distance or focal length from centre of dish),
2) Offset of the LNB (degree of rotation),
Setting No 1 (The focal length)
The focal length is the distance from the deepest point in the center of the dish to the front of the feedhorn on the LNB. On the Acer LNB this is 30mm inside. Others may vary. To start with, look for the markings on the side of the LNB and set the focal length in the middle of these markings. You can fine tune later.
For technical specialists: Refer to the instructions for your dish to obtain the correct focal length. If you do not have the instructions, you may need to use the formula below, where D = diameter of dish, d=depth of dish (measured in the center from the face to deepest point). Use a piece of string drawn tightly across the center of the face from one rim to the opposite rim to get an accurate face position. The focal length is = f
The formula is: f = D x D / 16 x d.
Example: D = 2.3m and d = 0.375m. f = 2.3 x 2.3 / 16 x 0.375 = 5.29/6 = 0.882m
Setting No 2 (The degree of rotation or polarization offset)
NB: On polar mount dishes, the 0 - 180° line should be parallel to the polar axis.
On fixed dishes, the polarization offset needs to be set on the LNB, which
is usually marked on the top with settings of 10, 20 30 and more degrees. See Picture 21. This should be measured assuming 0 degrees is at the 12 O’clock position (pointing straight up).
Hemisphere
Offset degrees
Rotate LNB*
Southern
Positive
Anti-clockwise
Northern
Negative
Clockwise
* When viewed from rear of LNB (as per Picture 21)
Example: For Johannesburg 53° offset requires the LNB to be rotated
anti-clockwise (to the left) by 53°
Picture 21
Side/rear view of Acer LNB
showing offset degrees
on the rear.
What is C-band?
What is C-band?C-band is a range of satellite transmission frequencies that TV and radio channels use to transmit to full-size satellite dishes.
How many channels can be received with a full-size C-band satellite dish?Full-size satellite dishes provide more viewing choices than any other TV delivery system, including cable. More than 250 channels transmit on a regular basis and another 250 transmit on an occasional basis. The "500 channel universe" is a reality with a full-size dish.
How big is a satellite dish?The size of the satellite dish you should buy depends on where you live in the United States or Canada. In the Central United States, you can use a dish that has a diameter of between six and eight feet. On either coast, an eight to ten-foot dish is recommended.
How much do full-size satellite dishes cost, and where can I buy one?Dishes range in price, but the average cost is $2,000. You can by a dish from a local satellite TV retailer, usually listed in the phone book under "Satellite" or "Television."
What is a transponder?Satellite TV and radio channels are transmitted back to earth via a transponder on a satellite. C-band satellites have 24 transponders.
Do all satellite TV channels require a subscription fee?No. More than 100 channels broadcast programming on a regular basis, and another 150 or more channels transmit wild feeds. Only C-band satellite TV provides hundreds of free channels and wild feeds.
What are wild feeds?Wild feeds are unannounced, free (not scrambled, no subscription required) satellite transmissions of sporting events, news and hundreds of syndicated shows such as Star Trek: Deep Space Nine. Satellite ORBIT "tracks" wild feeds and provides an extensive listing of them every month. See the "Wild Feeds" section of this site for an abbreviated listing of the most recent wild feeds. Satellite ORBIT publishes a complete listing each month.
What is VideoCipher II RS?VideoCipher II RS (VCII RS) is the scrambling system that most pay satellite TV channels use. To receive VCII RS pay channels, a VCII RS equipped satellite receiver is needed.
How much do pay channels cost?Pay channels range in price. Premium movies channels like HBO and Showtime are about $8 to $10 a month, and basic channels like ESPN and CNN can be purchased for $2 or less each per month. Programming is less expensive if a package is ordered. A package of two movie channels and 50 basic services can be purchased for as low as $30 to $35 per month. Discounts are available if a package is ordered for one year.
How do I order pay channel packages?A local satellite retailer can order programming for you-sometimes at a discount rate-or you can call the programming packagers directly.
Where can I get more information on full-size satellite TV?Contact a local satellite retailer for a demonstration.
What is the future of C-band?The future of C-band is here: 4DTV. 4DTV is a new type of receiver which can tune in four types of satellite transmissions: 1) Free, unscrambled analog channels and wild feeds 2) VideoCipher II Plus subscription services 3) Free DigiCipher II services 4) Subscription DigiCipher channels. DigiCipher transmissions are digital (not analog) and take up less transponder space, allowing for much more programming to be transmitted via each satellite.
What is currently available on 4DTV?This July, 88 DigiCipher II (DCII) digital channels were available with NextLevel System's (a division of General Instrument) new 4DTV combination DCII/VCII Plus receiver. At least another 38 channels are expected to become available by September. For more information, 4DTV's Web site is at www.4DTV.com.
1. A dish antenna for receiving transmissions from a transmitter such as a communications satellite comprising:
(a) a plurality of support ribs of selected length spaced in a radial manner and central support means for engaging and supporting the ribs, each rib having an inner end secured to the central support means and an outer end oriented away from the central support means, each rib comprising an outer sheath of flexible resilient plastic material transparent to microwaves having grooves along the side edges thereof defined by top and bottom walls, a hollow channel in the sheath extending along its length beneath the grooves therein, and a rigid support member within the channel in the sheath to provide structural support therefor;
(b) a plurality of antenna panels engaged between the ribs to form a dish having an anterior surface adapted to face the transmitter and a central axis adapted to symmetrically align a central point on the dish with the transmitter, each antenna panel formed of a microwave reflecting material and having a front surface, a rear surface, an inner edge oriented toward the central support means, an outer edge oriented away from the central support means, and opposed side edges extending between the inner edge and the outer edge of the panel, the opposed side edges of each panel received in the edge grooves of adjacent ribs such that the side edges of the panels are held between the top and bottom walls of the grooves, the front surface of each antenna panel being curved such that the anterior surface of the antenna as defined by the front surfaces of the panels is concave.
2. The dish antenna of claim 1 further including a peripheral ring which is generally round and has an inner surface generally oriented toward the central support means; and wherein each rib is of equal length and is generally coplanar with the central axis; and wherein the outer ends of the ribs are secured to the inner surface of the peripheral ring. 3. The dish antenna of claim 2 wherein the peripheral ring has ring grooves which receive the outer edges of the antenna panels. 4. The dish antenna of claim 1 wherein the opposed rib grooves of each rib closely approach each other; and wherein the edge of the antenna panel engaged by one groove of each rib terminates close to the edge of the antenna panel engaged by the second groove of the rib so that the transmissions which pass between the adjacent edges are minimized. 5. The dish antenna of claim 1 wherein the rib sheath is constructed of polyvinyl chloride plastic. 6. The dish antenna of claim 1 wherein the antenna panels are constructed of stainless steel mesh. 7. The dish antenna of claim 1 wherein the antenna panels are formed of an expanded, flattened aluminum mesh. 8. The dish antenna of claim 1 wherein the rib support members are made of steel. 9. The dish antenna of claim 1 wherein the central support means is a metal hub plate with a parabolic surface; wherein each rib is bent in a parabolic curve; wherein each antenna panel has a front surface forming a sector of a parabolic surface; and wherein the anterior surface of the dish as defined by the antenna panel front surfaces is generally parabolic. 10. The dish antenna of claim 1 wherein the channel in each rib sheath has laterally straight borders that underlie a portion of the groove bottom walls in parallel relation; and wherein the support members have rigid laterally straight surfaces that underlie and support the groove bottom wall. 11. A support rib adapted for use in a dish antenna structure comprising:
(a) an outer sheath of flexible, resilient plastic material transparent to microwaves, having grooves along the side edges thereof defined by top and bottom walls, and an inner hollow channel in the sheath extending along its length beneath the grooves therein; and
(b) a rigid inner support member fitted within the inner channel in the sheath to strengthen the rib and limit the longitudinal flexibility of the rib.
12. The support rib of claim 11 wherein the channel in the sheath and the support member are both rectangular in cross section with one side of the support member underlying a portion of the groove bottom wall. 13. The support rib of claim 11 wherein the rib sheath is formed of polyvinyl chloride. 14. The support rib of claim 11 wherein the support member is made of steel. 15. A kit for making a dish antenna structure comprising the combination of:
(a) a central hub;
(b) a plurality of peripheral ring segments adapted to be joined to form a round, peripheral ring which has an inner surface with a radius larger than the hub;
(c) a plurality of support ribs adapted to be spaced in a radial manner around the central hub, each having an inner end adapted to be secured to the hub and an outer end adapted to be secured to the peripheral ring, an outer sheath of flexible, resilient plastic material transparent to microwaves, having grooves along the side edges thereof defined by top and bottom walls, a hollow channel in the sheath extending along its length beneath the grooves therein, and a rigid support member within the channel in the sheath to provide structural support therefor;
(d) a plurality of antenna panels adapted to be engaged between the ribs to form a dish having an anterior surface adapted to face a transmitter and a central axis adapted to symmetrically align a central point on the dish with the transmitter, each antenna panel having a front surface, an inner edge adapted to be oriented toward the hub, an outer edge adapted to be oriented toward the peripheral ring and opposed side edges extending between the inner edge and the outer edge and adapted to be received by the edge grooves of adjacent ribs;
(e) means for securing each rib to the hub; and
(f) means for securing each rib to the peripheral ring.
16. The kit of claim 15 wherein each rib is of equal selected length and is adapted to extend from the hub to the peripheral ring; and wherein the front surface of each antenna panel is curved such that the anterior surface of the dish is concave. 17. The kit of claim 16 wherein the hub has a parabolic surface; wherein each antenna panel is curved to form a sector of a parabolic surface, wherein the support ribs are curved parabolically, and wherein the peripheral ring has a groove in its inner surface adapted to receive the outer edges of the antenna panels. 18. The kit of claim 15 wherein two rib grooves of each rib closely approach each other; and wherein the edges of the adjacent antenna panels are adapted to be held within the two grooves of each rib such that they terminate close to each other. 19. The kit of claim 17 further including a probe mount adapted to be secured to the central hub and to extend anteriorly therefrom; and a pickup probe adapted to be located on the probe mount in a position to effectively receive transmissions reflected from the antenna panels. 20. The kit of claim 16 further including a mounting bar which is adapted to mount to the hub to support the dish. 21. A method of forming radial dish support ribs comprising the steps of:
(a) providing a straight but flexible plastic rib sheath which has an inner longitudinal hollow channel therein along the length thereof;
(b) providing a rigid metallic support member which is fitted for insertion into the inner channel in the sheath;
(c) bending the support member to a selected generally parabolic curvature; and
(d) inserting the support member into the inner channel in the sheath, thereby curving the sheath to form a rib in the desired parabolic shape.
Description:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to antennas adapted to receive transmissions from communication satellites which orbit the earth, and in particular to dish antennas.
2. Background Art
The antenna dish provides a relatively wide surface for capturing satellite radio frequency transmissions and is often shaped parabolically to focus parallel intercepted microwaves upon a pickup probe to provide an augmented signal to the antenna user. Such shaped dishes have commonly been formed of stamped sheet metal (e.g., aluminum or stainless steel), either as one piece units or, for larger antennas, of multiple parts that are assembled on site. Dish antennas have also been formed from a plurality of wedged-shaped antenna sections of metal mesh which are capable of reflecting the transmitted radio waves and which are supported in the dish shape by rigid radial ribs. The ribs are appropriately shaped such that the antenna sections are held in position to form a parabolic surface. Dish antennas formed of sections of metal mesh allow light to pass therethrough, and thus may be more aesthetically acceptable than a solid sheet metal antenna. The metal mesh also allows air to pass through, resulting in a lower wind load than would exist in a solid antenna of the same size. A particular advantage of mesh antennas over solid metal dishes is that the mesh antenna can be shipped in pieces in compact packages whereas the solid dishes are extremely large and bulky, requiring special handling procedures, and consequently are expensive to ship.
While the performance of mesh antennas is generally comparable to solid dish antennas, it has been found that the supportive rigid ribs, which are made of metal, are capable themselves of reflecting microwaves. The surface of the metal rib section at the joint where the rib engages the mesh is typically displaced from the surface of the mesh. As a consequence, the microwaves reflected from the metal ribs may be slightly out of phase with the microwaves reflected from the metal surface. Because the supporting ribs must be of high strength and resistant to corrosion when exposed to weather, the ribs have typically been constructed of expensive high strength aluminum or stainless steel.
It is desirable to connect the antenna mesh sections to the supportive ribs without unduly stressing the mesh sections. Connection has been accomplished by fitting the edges of the mesh sections into longitudinal grooves located along the metal ribs. However, the panels generally cannot be tightly fit into the grooves in the metal ribs, and connectors, such as screws, are required to hold the mesh to the ribs.
SUMMARY OF THE INVENTION
The dish antenna structure of the present invention has wedge-shaped and sheet-like antenna panels, preferably formed of metal mesh, and radial support ribs which firmly engage the edges of the antenna panels to hold the same in the desired dish configuration. Each of the radial support ribs has an outer sheath of plastic material, e.g., polyvinyl chloride, which is flexible, resilient, and resistant to weathering by exposure to rain, wind and sunlight. Structural rigidity and strength is provided to the rib structure by an inner metal, preferably steel, support member held within a channel in the outer sheath. The metal member provides high strength and rigid support for the entire rib structure, enabling the rib to be produced at relatively low cost. Since the outer plastic sheath protects the inner metal member from contact with rain, the metal need not be corrosion resistant, and may be a common and inexpensive structural material, such as mild steel.
In a preferred form, the side edges of the rib sheaths have longintudinal grooves sized to admit the side edges of the wedge-shaped antenna panels and tightly engage the same without requiring other connectors.
The radially extending ribs are joined at their inner ends to a central support hub, which itself is preferably parabolically shaped, and are connected at their outer ends to a circular, peripheral ring, formed of a rigid, corrosion-resistant material such as aluminum, which is attached to the end of each radial rib and holds the same firmly in the desired position in the dish.
A particular advantage of the rib construction of the present invention is that the material of the rib sheath is transparent to microwaves. Thus, microwaves incident on the portion of the rib sheath which extends above the adjacent mesh panel will pass through the rib sheath and reflect off the panel, with no substantial difference in the phase of the reflected microwave off the panel under a portion of the sheath from microwaves reflected off of adjacent portions of the panels. The edges of adjacent panels fitted into the grooves in a rib terminate at positions closely adjacent to one another, with only a small break between the adjacent panels. Thus there is only a very limited amount of phase distortion of the reflected microwaves occurring because of this spaced joint.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an installed dish antenna structure in accordance with the invention.
FIG. 2 is a perspective view of a rib sheath lying straight with its rearward end angled.
FIG. 3 is a perspective view of an inner support member for a rib, curved parabolically with its rearward end angled.
FIG. 4 is a perspective view of a flexible rib supported in a curved position by a curved support member, the rearward ends of the rib and the support member being angled.
FIG. 5 is a cross section along line 5--5 of FIG. 1 showing a portion of an antenna section engaged by both a rib groove and a peripheral ring groove, and showing a ring segment connector.
FIG. 6 is a perspective view of one wedge-shaped reflective mesh panel.
FIG. 7 is a perspective view of the central support hub.
FIG. 8 is a perspective view of a section of the outer peripheral ring portion of the antenna.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the drawings, a preferred embodiment for a dish antenna structure constructed in accordance with the invention is shown generally at 10 in FIG. 1. The structural elements of the preferred dish antenna structure 10 include a plurality of uniformly constructed ribs 14 of selected length and a plurality of sheet-like antenna panels 18 also uniformly constructed. The ribs 14 and the antenna panels 18 are alternately spaced in a generally radial manner to form a dish 21. The dish has an anterior surface 11 adapted to face a transmitter, such as a communications satellite, and a central axis adapted to symmetrically align a central point on the dish with the transmitter. Each antenna panel 18 is preferably wedge-shaped, as best shown in FIG. 6, having a front surface 22 generally forming the anterior surface 11 of the antenna, a rear surface 24 oriented away from the anterior surface, an inner edge 25, an outer edge 26, and two opposed side edges 27 and 28.
Each rib 14 has an inner end 32 and an outer end 34. As best shown in FIG. 1, the inner ends 32 of all ribs are preferably coplanar where they are joined to a central support hub 30. In the preferred embodiment the hub plate 30 has holes 31 which are used to bolt the ribs in place, as is more fully explained below. Other means for centrally supporting the ribs, such as fixing the ribs to a central ring, will be evident to those skilled in the art. Each rib 14 extends outward in a generally radial direction from the hub 30. The hub 30 is curved, preferably in a parabolic fashion. The outer end 34 of each rib 14 is oriented away from the central support hub and is secured to the inner surface 36 of a circular peripheral ring 38.
Each antenna panel 18 is located with its inner edge 25 toward the support hub 30, its outer edge 26 away from the support hub, and its two opposed side edges 27 and 28 each oriented toward an adjacent rib 14. The antenna panels 18 are curved such that the anterior surface 11 defined by the front surfaces of the panels is generally concave. Preferably, each rib 14 is bent in a parabolic curve, the antenna panels 18 are shaped in sectors of a parabolic surface, and the dish anterior surface 11 is thus generally parabolic. This enables the antenna to most efficiently reflect and focus incoming radio frequency transmissions upon a point at which a pickup probe 39 may be located.
As shown in FIG. 2, each rib 14 in the preferred embodiment has a sheath 37 which has an inner hollow longitudinal channel 40 along the length of the rib. A rigid support member 42 may be fitted within the support channel 40 to strengthen the rib 14, as shown in FIG. 4, and to restrict the longitudinal flexibility of the rib. As shown in FIG. 3, the support member 42 may be bent, preferably in a parabolic curve, to define the curvature of the surrounding sheath 37.
The support member 42 is constructed of a strong material, such as steel, which provides most of the structural support for the dish antenna structure. As shown in FIG. 4, a first end 41 of the support member 42 may extend outward from the support channel 40 at its inner end and includes holes 47 through which the support member may be bolted to the hub 30. The inner end 32 of each rib 14 may thus be secured to the hub 30 by using the support member 42. In the preferred embodiment of the rib 14, rib grooves 44 are located longitudinally along the length of the ribs 14 and are used to connect the ribs to the antenna panels 18. The side edges 27 and 28 of an antenna panel 18 are respectively received by the rib grooves 44 of adjacent ribs. Each rib groove 44 has a bottom wall 45 and an opposed top wall 46 which engage the antenna panels 18 to hold the panels within the rib grooves, as shown in FIG. 5. Because the outer sheath of the rib is formed of a material (e.g., polyvinyl chloride) which is flexible and resilient, the rib groove walls can tightly engage the edges of the antenna panels inserted into the grooves. In the preferred embodiment, both the support channel 40 and the support member 42 are rectangular in cross section, with one face of the rectangle underlying a portion of the groove bottom walls 45 in parallel relation. Thus, a laterally straight border of the support channel 40 underlies a portion of groove bottom wall 45, and a rigid, laterally straight surface of the support member 42 underlies and supports the groove bottom wall 45, thereby enhancing the tightness with which the antenna panel side edges 27 and 28 may be engaged.
As shown in FIGS. 2, 4 and 5, the outer end 34 of the rib 14 is preferably angled. Similarly, the second end 43 of the support member 42 is also angled. As shown best in FIG. 5, the ends 34 and 43 are angled such that they generally meet the inner surface 36 of the peripheral ring. As also shown in FIG. 5, the ring 38 preferably has a peripheral ring groove 48 which receives and holds the outer edges 26 of the antenna panels 18. The ends of the ribs 14 may also be secured to the peripheral ring 38. In the preferred embodiment a bolt 49 is affixed to the outer end 34 of each rib and extends through support holes 51 located in the peripheral ring 38 at its junction with each rib 14 and is engaged with a nut to secure the rib in place.
The sheath of the rib 14 is made of a material which is transparent to microwaves. Because the rib sheaths are transparent to microwaves, the distortion of the microwave signal reflected by the dish is minimized. As shown in FIGS. 2 and 4, the opposed rib grooves 44 closely approach each other so that the edge 27 of one antenna panel engaged in a groove on one side of the rib terminates at a position closely adjacent to the edge 28 of the adjacent antenna panel engaged in the groove on the other side of the rib. This arrangement minimizes the spacing between the edges of the panels and the distortion produced by microwaves which might pass through the gap between the edges of adjacent antenna panels and reflect from the inner support member 42 to the pick up probe 39. Since the material of the sheath above the edges of the antenna panels is transparent to microwaves, it does not introduce phase distortions in the reflected signals.
The rib sheath 37 is also preferably corrosion resistant and waterproof, allowing the inner support member 42 to be constructed of strong but corrosion prone materials such as steel. In the preferred embodiment, the rib sheath is made from polyvinyl chloride, and the support members are made from steel.
The peripheral ring 38 may be formed in segments, allowing more convenient shipment, and in the preferred embodiment is constructed in two segments which are joined by segment connectors 50 bolted to both segments using bolt holes 52 and spanning the joint between them. The peripheral ring segments 38 are preferably constructed of a rigid, corrosion resistant material such as aluminum.
The antenna panels 18 are preferably constructed of an expanded, flattened, aluminum mesh. Other suitable materials may be substituted. For example, stainless steel mesh or other corrosion resistant material capable of reflecting microwaves may also be used for the antenna panels.
As shown in FIG. 1, the preferred embodiment includes a mounting bar 53 which is rotatably mounted to the hub 30 such that, when the mounting bar is fixed in position in the ground, the orientation of the dish may be adjusted. The antenna also includes a probe mount 54 secured to the central hub 30 and extending therefrom such that the pickup probe 39 may be located on the probe mount in a position to effectively receive microwaves reflected from the antenna sections.
While the dish antenna structure is shown assembled in FIG. 1, it is commonly shipped to the user's location in kit form. Each part in the kit is, of course, adapted to relate to the others as described above.
The outer sheath 37 can be formed from a continuous plastic extrusion having the cross-sectional shape shown in FIG. 2 and can be cut to the desired lengths for the ribs. The extruded plastic sheaths are formed straight but the sheath is sufficiently flexible to assume the curve of the support member 42 as the support member is inserted into the support channel 40. The support member 42 itself may be formed of straight hollow tube stock which is bent to a selected parabolic curvature in a press. The step of extruding the rib sheath is preferably carried out using a commercially available apparatus for extruding plastic such as polyvinyl chloride. The bent support members 42 may be manually inserted into the straight rib sheaths which distort as the support member is inserted to assume the desired parabolic shape for the rib.
It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.
How many channels can be received with a full-size C-band satellite dish?Full-size satellite dishes provide more viewing choices than any other TV delivery system, including cable. More than 250 channels transmit on a regular basis and another 250 transmit on an occasional basis. The "500 channel universe" is a reality with a full-size dish.
How big is a satellite dish?The size of the satellite dish you should buy depends on where you live in the United States or Canada. In the Central United States, you can use a dish that has a diameter of between six and eight feet. On either coast, an eight to ten-foot dish is recommended.
How much do full-size satellite dishes cost, and where can I buy one?Dishes range in price, but the average cost is $2,000. You can by a dish from a local satellite TV retailer, usually listed in the phone book under "Satellite" or "Television."
What is a transponder?Satellite TV and radio channels are transmitted back to earth via a transponder on a satellite. C-band satellites have 24 transponders.
Do all satellite TV channels require a subscription fee?No. More than 100 channels broadcast programming on a regular basis, and another 150 or more channels transmit wild feeds. Only C-band satellite TV provides hundreds of free channels and wild feeds.
What are wild feeds?Wild feeds are unannounced, free (not scrambled, no subscription required) satellite transmissions of sporting events, news and hundreds of syndicated shows such as Star Trek: Deep Space Nine. Satellite ORBIT "tracks" wild feeds and provides an extensive listing of them every month. See the "Wild Feeds" section of this site for an abbreviated listing of the most recent wild feeds. Satellite ORBIT publishes a complete listing each month.
What is VideoCipher II RS?VideoCipher II RS (VCII RS) is the scrambling system that most pay satellite TV channels use. To receive VCII RS pay channels, a VCII RS equipped satellite receiver is needed.
How much do pay channels cost?Pay channels range in price. Premium movies channels like HBO and Showtime are about $8 to $10 a month, and basic channels like ESPN and CNN can be purchased for $2 or less each per month. Programming is less expensive if a package is ordered. A package of two movie channels and 50 basic services can be purchased for as low as $30 to $35 per month. Discounts are available if a package is ordered for one year.
How do I order pay channel packages?A local satellite retailer can order programming for you-sometimes at a discount rate-or you can call the programming packagers directly.
Where can I get more information on full-size satellite TV?Contact a local satellite retailer for a demonstration.
What is the future of C-band?The future of C-band is here: 4DTV. 4DTV is a new type of receiver which can tune in four types of satellite transmissions: 1) Free, unscrambled analog channels and wild feeds 2) VideoCipher II Plus subscription services 3) Free DigiCipher II services 4) Subscription DigiCipher channels. DigiCipher transmissions are digital (not analog) and take up less transponder space, allowing for much more programming to be transmitted via each satellite.
What is currently available on 4DTV?This July, 88 DigiCipher II (DCII) digital channels were available with NextLevel System's (a division of General Instrument) new 4DTV combination DCII/VCII Plus receiver. At least another 38 channels are expected to become available by September. For more information, 4DTV's Web site is at www.4DTV.com.
1. A dish antenna for receiving transmissions from a transmitter such as a communications satellite comprising:
(a) a plurality of support ribs of selected length spaced in a radial manner and central support means for engaging and supporting the ribs, each rib having an inner end secured to the central support means and an outer end oriented away from the central support means, each rib comprising an outer sheath of flexible resilient plastic material transparent to microwaves having grooves along the side edges thereof defined by top and bottom walls, a hollow channel in the sheath extending along its length beneath the grooves therein, and a rigid support member within the channel in the sheath to provide structural support therefor;
(b) a plurality of antenna panels engaged between the ribs to form a dish having an anterior surface adapted to face the transmitter and a central axis adapted to symmetrically align a central point on the dish with the transmitter, each antenna panel formed of a microwave reflecting material and having a front surface, a rear surface, an inner edge oriented toward the central support means, an outer edge oriented away from the central support means, and opposed side edges extending between the inner edge and the outer edge of the panel, the opposed side edges of each panel received in the edge grooves of adjacent ribs such that the side edges of the panels are held between the top and bottom walls of the grooves, the front surface of each antenna panel being curved such that the anterior surface of the antenna as defined by the front surfaces of the panels is concave.
2. The dish antenna of claim 1 further including a peripheral ring which is generally round and has an inner surface generally oriented toward the central support means; and wherein each rib is of equal length and is generally coplanar with the central axis; and wherein the outer ends of the ribs are secured to the inner surface of the peripheral ring. 3. The dish antenna of claim 2 wherein the peripheral ring has ring grooves which receive the outer edges of the antenna panels. 4. The dish antenna of claim 1 wherein the opposed rib grooves of each rib closely approach each other; and wherein the edge of the antenna panel engaged by one groove of each rib terminates close to the edge of the antenna panel engaged by the second groove of the rib so that the transmissions which pass between the adjacent edges are minimized. 5. The dish antenna of claim 1 wherein the rib sheath is constructed of polyvinyl chloride plastic. 6. The dish antenna of claim 1 wherein the antenna panels are constructed of stainless steel mesh. 7. The dish antenna of claim 1 wherein the antenna panels are formed of an expanded, flattened aluminum mesh. 8. The dish antenna of claim 1 wherein the rib support members are made of steel. 9. The dish antenna of claim 1 wherein the central support means is a metal hub plate with a parabolic surface; wherein each rib is bent in a parabolic curve; wherein each antenna panel has a front surface forming a sector of a parabolic surface; and wherein the anterior surface of the dish as defined by the antenna panel front surfaces is generally parabolic. 10. The dish antenna of claim 1 wherein the channel in each rib sheath has laterally straight borders that underlie a portion of the groove bottom walls in parallel relation; and wherein the support members have rigid laterally straight surfaces that underlie and support the groove bottom wall. 11. A support rib adapted for use in a dish antenna structure comprising:
(a) an outer sheath of flexible, resilient plastic material transparent to microwaves, having grooves along the side edges thereof defined by top and bottom walls, and an inner hollow channel in the sheath extending along its length beneath the grooves therein; and
(b) a rigid inner support member fitted within the inner channel in the sheath to strengthen the rib and limit the longitudinal flexibility of the rib.
12. The support rib of claim 11 wherein the channel in the sheath and the support member are both rectangular in cross section with one side of the support member underlying a portion of the groove bottom wall. 13. The support rib of claim 11 wherein the rib sheath is formed of polyvinyl chloride. 14. The support rib of claim 11 wherein the support member is made of steel. 15. A kit for making a dish antenna structure comprising the combination of:
(a) a central hub;
(b) a plurality of peripheral ring segments adapted to be joined to form a round, peripheral ring which has an inner surface with a radius larger than the hub;
(c) a plurality of support ribs adapted to be spaced in a radial manner around the central hub, each having an inner end adapted to be secured to the hub and an outer end adapted to be secured to the peripheral ring, an outer sheath of flexible, resilient plastic material transparent to microwaves, having grooves along the side edges thereof defined by top and bottom walls, a hollow channel in the sheath extending along its length beneath the grooves therein, and a rigid support member within the channel in the sheath to provide structural support therefor;
(d) a plurality of antenna panels adapted to be engaged between the ribs to form a dish having an anterior surface adapted to face a transmitter and a central axis adapted to symmetrically align a central point on the dish with the transmitter, each antenna panel having a front surface, an inner edge adapted to be oriented toward the hub, an outer edge adapted to be oriented toward the peripheral ring and opposed side edges extending between the inner edge and the outer edge and adapted to be received by the edge grooves of adjacent ribs;
(e) means for securing each rib to the hub; and
(f) means for securing each rib to the peripheral ring.
16. The kit of claim 15 wherein each rib is of equal selected length and is adapted to extend from the hub to the peripheral ring; and wherein the front surface of each antenna panel is curved such that the anterior surface of the dish is concave. 17. The kit of claim 16 wherein the hub has a parabolic surface; wherein each antenna panel is curved to form a sector of a parabolic surface, wherein the support ribs are curved parabolically, and wherein the peripheral ring has a groove in its inner surface adapted to receive the outer edges of the antenna panels. 18. The kit of claim 15 wherein two rib grooves of each rib closely approach each other; and wherein the edges of the adjacent antenna panels are adapted to be held within the two grooves of each rib such that they terminate close to each other. 19. The kit of claim 17 further including a probe mount adapted to be secured to the central hub and to extend anteriorly therefrom; and a pickup probe adapted to be located on the probe mount in a position to effectively receive transmissions reflected from the antenna panels. 20. The kit of claim 16 further including a mounting bar which is adapted to mount to the hub to support the dish. 21. A method of forming radial dish support ribs comprising the steps of:
(a) providing a straight but flexible plastic rib sheath which has an inner longitudinal hollow channel therein along the length thereof;
(b) providing a rigid metallic support member which is fitted for insertion into the inner channel in the sheath;
(c) bending the support member to a selected generally parabolic curvature; and
(d) inserting the support member into the inner channel in the sheath, thereby curving the sheath to form a rib in the desired parabolic shape.
Description:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to antennas adapted to receive transmissions from communication satellites which orbit the earth, and in particular to dish antennas.
2. Background Art
The antenna dish provides a relatively wide surface for capturing satellite radio frequency transmissions and is often shaped parabolically to focus parallel intercepted microwaves upon a pickup probe to provide an augmented signal to the antenna user. Such shaped dishes have commonly been formed of stamped sheet metal (e.g., aluminum or stainless steel), either as one piece units or, for larger antennas, of multiple parts that are assembled on site. Dish antennas have also been formed from a plurality of wedged-shaped antenna sections of metal mesh which are capable of reflecting the transmitted radio waves and which are supported in the dish shape by rigid radial ribs. The ribs are appropriately shaped such that the antenna sections are held in position to form a parabolic surface. Dish antennas formed of sections of metal mesh allow light to pass therethrough, and thus may be more aesthetically acceptable than a solid sheet metal antenna. The metal mesh also allows air to pass through, resulting in a lower wind load than would exist in a solid antenna of the same size. A particular advantage of mesh antennas over solid metal dishes is that the mesh antenna can be shipped in pieces in compact packages whereas the solid dishes are extremely large and bulky, requiring special handling procedures, and consequently are expensive to ship.
While the performance of mesh antennas is generally comparable to solid dish antennas, it has been found that the supportive rigid ribs, which are made of metal, are capable themselves of reflecting microwaves. The surface of the metal rib section at the joint where the rib engages the mesh is typically displaced from the surface of the mesh. As a consequence, the microwaves reflected from the metal ribs may be slightly out of phase with the microwaves reflected from the metal surface. Because the supporting ribs must be of high strength and resistant to corrosion when exposed to weather, the ribs have typically been constructed of expensive high strength aluminum or stainless steel.
It is desirable to connect the antenna mesh sections to the supportive ribs without unduly stressing the mesh sections. Connection has been accomplished by fitting the edges of the mesh sections into longitudinal grooves located along the metal ribs. However, the panels generally cannot be tightly fit into the grooves in the metal ribs, and connectors, such as screws, are required to hold the mesh to the ribs.
SUMMARY OF THE INVENTION
The dish antenna structure of the present invention has wedge-shaped and sheet-like antenna panels, preferably formed of metal mesh, and radial support ribs which firmly engage the edges of the antenna panels to hold the same in the desired dish configuration. Each of the radial support ribs has an outer sheath of plastic material, e.g., polyvinyl chloride, which is flexible, resilient, and resistant to weathering by exposure to rain, wind and sunlight. Structural rigidity and strength is provided to the rib structure by an inner metal, preferably steel, support member held within a channel in the outer sheath. The metal member provides high strength and rigid support for the entire rib structure, enabling the rib to be produced at relatively low cost. Since the outer plastic sheath protects the inner metal member from contact with rain, the metal need not be corrosion resistant, and may be a common and inexpensive structural material, such as mild steel.
In a preferred form, the side edges of the rib sheaths have longintudinal grooves sized to admit the side edges of the wedge-shaped antenna panels and tightly engage the same without requiring other connectors.
The radially extending ribs are joined at their inner ends to a central support hub, which itself is preferably parabolically shaped, and are connected at their outer ends to a circular, peripheral ring, formed of a rigid, corrosion-resistant material such as aluminum, which is attached to the end of each radial rib and holds the same firmly in the desired position in the dish.
A particular advantage of the rib construction of the present invention is that the material of the rib sheath is transparent to microwaves. Thus, microwaves incident on the portion of the rib sheath which extends above the adjacent mesh panel will pass through the rib sheath and reflect off the panel, with no substantial difference in the phase of the reflected microwave off the panel under a portion of the sheath from microwaves reflected off of adjacent portions of the panels. The edges of adjacent panels fitted into the grooves in a rib terminate at positions closely adjacent to one another, with only a small break between the adjacent panels. Thus there is only a very limited amount of phase distortion of the reflected microwaves occurring because of this spaced joint.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an installed dish antenna structure in accordance with the invention.
FIG. 2 is a perspective view of a rib sheath lying straight with its rearward end angled.
FIG. 3 is a perspective view of an inner support member for a rib, curved parabolically with its rearward end angled.
FIG. 4 is a perspective view of a flexible rib supported in a curved position by a curved support member, the rearward ends of the rib and the support member being angled.
FIG. 5 is a cross section along line 5--5 of FIG. 1 showing a portion of an antenna section engaged by both a rib groove and a peripheral ring groove, and showing a ring segment connector.
FIG. 6 is a perspective view of one wedge-shaped reflective mesh panel.
FIG. 7 is a perspective view of the central support hub.
FIG. 8 is a perspective view of a section of the outer peripheral ring portion of the antenna.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the drawings, a preferred embodiment for a dish antenna structure constructed in accordance with the invention is shown generally at 10 in FIG. 1. The structural elements of the preferred dish antenna structure 10 include a plurality of uniformly constructed ribs 14 of selected length and a plurality of sheet-like antenna panels 18 also uniformly constructed. The ribs 14 and the antenna panels 18 are alternately spaced in a generally radial manner to form a dish 21. The dish has an anterior surface 11 adapted to face a transmitter, such as a communications satellite, and a central axis adapted to symmetrically align a central point on the dish with the transmitter. Each antenna panel 18 is preferably wedge-shaped, as best shown in FIG. 6, having a front surface 22 generally forming the anterior surface 11 of the antenna, a rear surface 24 oriented away from the anterior surface, an inner edge 25, an outer edge 26, and two opposed side edges 27 and 28.
Each rib 14 has an inner end 32 and an outer end 34. As best shown in FIG. 1, the inner ends 32 of all ribs are preferably coplanar where they are joined to a central support hub 30. In the preferred embodiment the hub plate 30 has holes 31 which are used to bolt the ribs in place, as is more fully explained below. Other means for centrally supporting the ribs, such as fixing the ribs to a central ring, will be evident to those skilled in the art. Each rib 14 extends outward in a generally radial direction from the hub 30. The hub 30 is curved, preferably in a parabolic fashion. The outer end 34 of each rib 14 is oriented away from the central support hub and is secured to the inner surface 36 of a circular peripheral ring 38.
Each antenna panel 18 is located with its inner edge 25 toward the support hub 30, its outer edge 26 away from the support hub, and its two opposed side edges 27 and 28 each oriented toward an adjacent rib 14. The antenna panels 18 are curved such that the anterior surface 11 defined by the front surfaces of the panels is generally concave. Preferably, each rib 14 is bent in a parabolic curve, the antenna panels 18 are shaped in sectors of a parabolic surface, and the dish anterior surface 11 is thus generally parabolic. This enables the antenna to most efficiently reflect and focus incoming radio frequency transmissions upon a point at which a pickup probe 39 may be located.
As shown in FIG. 2, each rib 14 in the preferred embodiment has a sheath 37 which has an inner hollow longitudinal channel 40 along the length of the rib. A rigid support member 42 may be fitted within the support channel 40 to strengthen the rib 14, as shown in FIG. 4, and to restrict the longitudinal flexibility of the rib. As shown in FIG. 3, the support member 42 may be bent, preferably in a parabolic curve, to define the curvature of the surrounding sheath 37.
The support member 42 is constructed of a strong material, such as steel, which provides most of the structural support for the dish antenna structure. As shown in FIG. 4, a first end 41 of the support member 42 may extend outward from the support channel 40 at its inner end and includes holes 47 through which the support member may be bolted to the hub 30. The inner end 32 of each rib 14 may thus be secured to the hub 30 by using the support member 42. In the preferred embodiment of the rib 14, rib grooves 44 are located longitudinally along the length of the ribs 14 and are used to connect the ribs to the antenna panels 18. The side edges 27 and 28 of an antenna panel 18 are respectively received by the rib grooves 44 of adjacent ribs. Each rib groove 44 has a bottom wall 45 and an opposed top wall 46 which engage the antenna panels 18 to hold the panels within the rib grooves, as shown in FIG. 5. Because the outer sheath of the rib is formed of a material (e.g., polyvinyl chloride) which is flexible and resilient, the rib groove walls can tightly engage the edges of the antenna panels inserted into the grooves. In the preferred embodiment, both the support channel 40 and the support member 42 are rectangular in cross section, with one face of the rectangle underlying a portion of the groove bottom walls 45 in parallel relation. Thus, a laterally straight border of the support channel 40 underlies a portion of groove bottom wall 45, and a rigid, laterally straight surface of the support member 42 underlies and supports the groove bottom wall 45, thereby enhancing the tightness with which the antenna panel side edges 27 and 28 may be engaged.
As shown in FIGS. 2, 4 and 5, the outer end 34 of the rib 14 is preferably angled. Similarly, the second end 43 of the support member 42 is also angled. As shown best in FIG. 5, the ends 34 and 43 are angled such that they generally meet the inner surface 36 of the peripheral ring. As also shown in FIG. 5, the ring 38 preferably has a peripheral ring groove 48 which receives and holds the outer edges 26 of the antenna panels 18. The ends of the ribs 14 may also be secured to the peripheral ring 38. In the preferred embodiment a bolt 49 is affixed to the outer end 34 of each rib and extends through support holes 51 located in the peripheral ring 38 at its junction with each rib 14 and is engaged with a nut to secure the rib in place.
The sheath of the rib 14 is made of a material which is transparent to microwaves. Because the rib sheaths are transparent to microwaves, the distortion of the microwave signal reflected by the dish is minimized. As shown in FIGS. 2 and 4, the opposed rib grooves 44 closely approach each other so that the edge 27 of one antenna panel engaged in a groove on one side of the rib terminates at a position closely adjacent to the edge 28 of the adjacent antenna panel engaged in the groove on the other side of the rib. This arrangement minimizes the spacing between the edges of the panels and the distortion produced by microwaves which might pass through the gap between the edges of adjacent antenna panels and reflect from the inner support member 42 to the pick up probe 39. Since the material of the sheath above the edges of the antenna panels is transparent to microwaves, it does not introduce phase distortions in the reflected signals.
The rib sheath 37 is also preferably corrosion resistant and waterproof, allowing the inner support member 42 to be constructed of strong but corrosion prone materials such as steel. In the preferred embodiment, the rib sheath is made from polyvinyl chloride, and the support members are made from steel.
The peripheral ring 38 may be formed in segments, allowing more convenient shipment, and in the preferred embodiment is constructed in two segments which are joined by segment connectors 50 bolted to both segments using bolt holes 52 and spanning the joint between them. The peripheral ring segments 38 are preferably constructed of a rigid, corrosion resistant material such as aluminum.
The antenna panels 18 are preferably constructed of an expanded, flattened, aluminum mesh. Other suitable materials may be substituted. For example, stainless steel mesh or other corrosion resistant material capable of reflecting microwaves may also be used for the antenna panels.
As shown in FIG. 1, the preferred embodiment includes a mounting bar 53 which is rotatably mounted to the hub 30 such that, when the mounting bar is fixed in position in the ground, the orientation of the dish may be adjusted. The antenna also includes a probe mount 54 secured to the central hub 30 and extending therefrom such that the pickup probe 39 may be located on the probe mount in a position to effectively receive microwaves reflected from the antenna sections.
While the dish antenna structure is shown assembled in FIG. 1, it is commonly shipped to the user's location in kit form. Each part in the kit is, of course, adapted to relate to the others as described above.
The outer sheath 37 can be formed from a continuous plastic extrusion having the cross-sectional shape shown in FIG. 2 and can be cut to the desired lengths for the ribs. The extruded plastic sheaths are formed straight but the sheath is sufficiently flexible to assume the curve of the support member 42 as the support member is inserted into the support channel 40. The support member 42 itself may be formed of straight hollow tube stock which is bent to a selected parabolic curvature in a press. The step of extruding the rib sheath is preferably carried out using a commercially available apparatus for extruding plastic such as polyvinyl chloride. The bent support members 42 may be manually inserted into the straight rib sheaths which distort as the support member is inserted to assume the desired parabolic shape for the rib.
It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.
How To Build A Parabolic Dish?
How do you build a Parabolic dish?
While it is difficult to build a parabolic shape with a large amount of precision (in the absence of expensive machinery), there are a few tricks which allow anyone to build a crude parabolic dish.
One method is to cut out a two dimensional parabolic shape from some rigid material and then use it to help you model some three dimensional shape (out of aluminum foil or chicken wire, for instance). The focus of the parabola is located at the point (0,p) where .
Although it is more difficult to implement, nature provides us with a far more accurate way of obtaining a parabolic shape. If a body of water is in a rotating container (and the liquid and the container are rotating together at the same speed), the surface of the water takes the shape of a near perfect parabolic shape. The focus of the parabolic shape depends on the rate of the rotation and also on the density of the liquid (if you were using something other than water). This approach is probably more interesting for those interested in the optics of parabolic shapes.
While it is difficult to build a parabolic shape with a large amount of precision (in the absence of expensive machinery), there are a few tricks which allow anyone to build a crude parabolic dish.
One method is to cut out a two dimensional parabolic shape from some rigid material and then use it to help you model some three dimensional shape (out of aluminum foil or chicken wire, for instance). The focus of the parabola is located at the point (0,p) where .
Although it is more difficult to implement, nature provides us with a far more accurate way of obtaining a parabolic shape. If a body of water is in a rotating container (and the liquid and the container are rotating together at the same speed), the surface of the water takes the shape of a near perfect parabolic shape. The focus of the parabolic shape depends on the rate of the rotation and also on the density of the liquid (if you were using something other than water). This approach is probably more interesting for those interested in the optics of parabolic shapes.
Satellite Dish Basics:
Transmitting Dish: A satellite dish is just a special kind of antenna designed to focus the signals on a specific point. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam. The curved dish reflects energy from the feed horn, generating a narrow beam. Receiving Dish: The dish on the receiving end can't transmit information; it can only receive it. The receiving dish works in the exact opposite way of the transmitter. When a beam hits the curved dish, the parabola shape reflects the radio signal inward onto a particular point, just like a concave mirror focuses light onto a particular point. In this case, the point is the dish's feed horn having an LNB installed, which passes the signal on to the receiving equipment. In an ideal setup, there aren't any major obstacles between the satellite and the dish, so the dish receives a clear signal. In some systems, the dish needs to pick up signals from two or more satellites at the same time. The satellites may be close enough together that a regular dish with a single horn can pick up signals from both. This compromises quality somewhat, because the dish isn't aimed directly at one or more of the satellites. A new dish design uses two or more horns to pick up different satellite signals. As the beams from different satellites hit the curved dish, they reflect at different angles so that one beam hits one of the horns and another beam hits a different horn. The central element in the feed horn is the low noise blockdown converter or LNB. The LNB amplifies the radio signal bouncing off the dish and filters out the noise (radio signals not carrying programming). The LNB passes the amplified, filtered signal to the satellite receiver inside the viewer's house.
Digital Satellite Receivers
Neoosat SX 6900, 9600, 9800
Supermax 6000 Ci
Humax
Winesat Digibox 500
Panasonic Digibox
Opertel 2000 Ci
Fortic Star
Technosat 777
Astrovox
Metabox (Pin Code)
Yuri 300
Eurobox
Pareezma
Medistar
Samsung DSR 9400
Nokia 9600
Starsat
Quries
Star DTH
Pacebox
DataBox
Pace Sky Box
Powermid
Philips VL1200 Wireless TV Link
Thomson VS 540 U
Freeview.co.uk
Wideband TV Aerial
Magic Eye
Giga Video
Iredto Cam
Crep-Mex Card
Via Guard Card
Multicam
Mansat
Prime Focus Antenna
Viaccess
Bluekiss, BSNL
Wavefrontier Antenna
Yagi Antenna
Flipup Antenna
DROMAX Dish
Sapcelink Dish Antenna
REN TV
Doordarshan DTHCAmbridge LNBs
Trowdil Dish
Looksat
STAB Motor
Dishtrack
Videoguard
ADD for Cable Operators
Pehla Plus
Orbit.net
Supermax FT 9900
Satsw
Rdi-sat.com
Scrambling
Iredo wider
Airbrick Dishes
Zee STB
Startrack
Teflon Biscuits
Star TV Network Decoder
Supermax 6000 Ci
Humax
Winesat Digibox 500
Panasonic Digibox
Opertel 2000 Ci
Fortic Star
Technosat 777
Astrovox
Metabox (Pin Code)
Yuri 300
Eurobox
Pareezma
Medistar
Samsung DSR 9400
Nokia 9600
Starsat
Quries
Star DTH
Pacebox
DataBox
Pace Sky Box
Powermid
Philips VL1200 Wireless TV Link
Thomson VS 540 U
Freeview.co.uk
Wideband TV Aerial
Magic Eye
Giga Video
Iredto Cam
Crep-Mex Card
Via Guard Card
Multicam
Mansat
Prime Focus Antenna
Viaccess
Bluekiss, BSNL
Wavefrontier Antenna
Yagi Antenna
Flipup Antenna
DROMAX Dish
Sapcelink Dish Antenna
REN TV
Doordarshan DTHCAmbridge LNBs
Trowdil Dish
Looksat
STAB Motor
Dishtrack
Videoguard
ADD for Cable Operators
Pehla Plus
Orbit.net
Supermax FT 9900
Satsw
Rdi-sat.com
Scrambling
Iredo wider
Airbrick Dishes
Zee STB
Startrack
Teflon Biscuits
Star TV Network Decoder
Satellite dish is a parabolic television antenna
Background
A satellite dish is a parabolic television antenna that receives signals from communication satellites in orbit around the earth. Its sole function is to provide the television viewer with a wider variety of channels.
The first communications satellite—Echo I—was launched by the United States in 1960, transmitting telephone signals. In 1961 Relay began transmitting television signals, and in the same year Syncom established itself as the first geosynchronous satellite capable of transmitting signals to one particular section of the earth's surface continuously.
The rapid advances in communication satellite technology were not simultaneously matched by advances in satellite dish use and technology. Television broadcasting began with individual stations that could only serve a limited area. Television networks had to provide their affiliate stations with recordings of programs if they wished to provide nationwide service. Satellite television was not widely available until the 1970s, when cable television stations equipped with satellite dishes received signals that were then sent to subscribers by coaxial cable. By 1976, there were 130 satellite dishes owned by cable companies, and by 1980, every cable television station had at least one satellite dish.
About that time personal satellite dish earth stations were selling for approximately $35,000 per unit. Taylor Howard, an employee at Stanford University who was well-versed in the usefulness of satellites as relayers of data, is credited with designing the first satellite dish for personal use. Howard's dish, which was placed into operation on September 14, 1976, was made of aluminum mesh and was about 16 feet (5 meters) wide. By 1980,5,000 satellite dishes had been purchased for home use. In 1984 alone 500,000 were installed. Recent reports state that there are 3.7 million owners of home satellite dishes worldwide, and the number will continue to grow.
A typical commercial satellite dish of the 1970s was made of heavy fiberglass, and the dish itself, at its smallest size, had a diameter of about ten feet (three meters). Since then, satellite dish design has shifted toward light-weight, aluminum mesh dishes (similar to Howard's homemade dish), some of which are inexpensive and small (three feet, or one meter, in diameter is typical), with many sections (petals) that can be easily assembled. England, Japan, and Germany, have led the way with direct broadcast TV, which sends signals directly to the viewer's dish, but the United States has yet to do so. This trend would yield smaller, more affordable satellite dishes and regulated satellite programming.
Raw Materials
The basic satellite dish consists of the following materials:
A parabolic reflector made of fiberglass or metal, usually aluminum, with a protruding steel feed horn and amplifier in its middle.
A steel actuator that enables the dish to receive signals from more than one satellite.
A metal (usually aluminum) shroud measuring about 6 to 18 inches (15 to 45 centimeters) in height. It is installed on the dish's circumference perpendicularly to reduce side interference.
Cables, most likely made from vinyl tubing and copper wiring.
The Manufacturing Process
1 To make fiberglass suitable for dish manufacture, a sheet molding compound mixture that includes reflective metallic material and ultraviolet scattering compositions is mixed with resin, calcium carbonate, and a catalyst cure. This mixture forms a paste that is poured onto a sheet of polyethylene film that has fiberglass added in chopped form. The result is a sheet layered with the compound paste, fiberglass, and the polyethylene film.
2 This sheet is then pressed at 89 degrees Fahrenheit (30 degrees Celsius) to mature. To shape the sheet into the desired parabolic shape, it is pressed at high pressure (of 1,400-2,200 metric tons). The dish is then trimmed, cooled, and painted. After the paint has dried, the dish is packed for shipment in sturdy boxes.
3 For metallic dishes, the common metal of choice is aluminum. This type of dish can be assembled in sections called petals, or all at once. An aluminum plate is perforated with a punching die, creating tiny holes. The size of these holes are contingent on the manufacturer's preference. Larger holes mean greater loss of the signal, so fairly small holes are selected. Another factor in the selection of hole size is the power of the broadcasting satellite. Newer, more powerful satellites require a hole size that is approximately half that required for older, less powerful satellites. The newly perforated aluminum plate is then heated, stretched over a mold, cooled, and trimmed. A paint powder coating for protection is then applied using an electrostatic charge, in which the paint is given an opposite electrical charge from the plate. The dish or petal is then heated to melt the powder and seal the paint on. The petals are usually sealed together with ribs in the factory.
4 Mesh petals are made from aluminum that is extruded—forced into a die of the proper shape. They are usually joined together on site by sliding them into aluminum ribs that attach to the hub and then securing them with metal pins.
Installation
5 All dishes, when complete, will have the necessary equipment (the feed horn, the amplifier, etc.) installed in the factory. When the dish has been set up at the local dealer, it is transported to the site location on a open trailer. Satellite dishes can be installed either by professionals or by the purchaser, with assistance from the retailer if necessary. The method selected depends upon the size of the dish and the mechanical expertise of the purchaser.
6 An installation site reasonably clear of obstructions not more than 246 feet (75 meters) from the house is selected. Site selection is also contingent on local building codes and the possibility of microwave interference from radio and television towers in the vicinity. Once a site is selected, the base must be installed first. The base of most satellite dishes consists of a concrete foundation that extends below the frost line. A clayey soil is excellent, while sandy or rocky soil requires more concrete. A base tube filled with concrete is then set into the concrete foundation.
Some satellite dishes require a slab mount installation, a method considered to be more stable than typical base construction. In some cases, slab mount installation is necessary since the site selected for the placement of the satellite dish is unstable. The slab is generally 1.6 feet (.5 meter) square and 3.2 feet (1 meter) deep. Soil is excavated to the proper depth and the concrete is poured. A triangular steel mount fixture is then embedded into the concrete.
7 Next, the pedestal is attached to either the base tube or the triangular steel mount fixture. The elevation arm is then attached to the pedestal.
Alignment
8 The mounted satellite dish must be aligned in order to point toward the satellite. The angle at which the dish is eventually situated will vary according to which satellite is selected and at what latitude the dish is located. Coaxial cables connect the satellite to the receiver that is located in the house near the television. A trench must be dug for these cables, which are placed into a pipe before being buried.
Quality Control
Satellite dishes for consumer use are not usually required to undergo rigorous tests with set standards, but some parameters are generally met. For example, so that the microwaves are received properly, the surface of the dish should be as smooth as possible and its parabolic shape should be exact. It must also be composed at least partially of metal, otherwise the microwaves will not reflect. If the dish is either mesh or perforated aluminum, the holes must be relatively tiny to minimize loss. Dish size is important; it should match that appropriate to the latitude. The mount should be sturdy, and the dish aligned properly for maximum reception.
Members and joints are tested and compared to the American Steel Construction Institute or the American Aluminum Association methods rules, whichever apply. The satellite dish should be built to withstand high winds, snow, ice, rain, and extreme temperatures.
After the dish is installed, the owner is generally responsible for cleaning it twice a year, more if necessary, tightening and lubricating all bolts once a year, and trimming obstructive weeds and trees from around it. In rare occasions, the owner must adjust the alignment to correct bad reception.
The Future
Satellite dishes will become ubiquitous in upcoming years. More communication satellites will certainly be launched, and the growth explosion in individual satellite dish ownership will continue. One factor that should affect home satellite dish ownership in the near future is the switchover to more powerful satellites that will transmit signals in the K band (12 GHz). Because most of the present satellite dishes accept signals in the C band (3.7 to 4.2 GHz), owners of C band satellite dishes will have to convert them to K band. Researchers and designers are contemplating even smaller dishes that could be placed on a rooftop or outside a window and still function as well as the larger satellite dishes of today.
Some experts see the growth of satellite television as a revolution that is less concerned with crystal clear images of old sitcoms than with the possibilities of two-way communication that universal dish ownership would promote. Satellite television will be used to pay bills, shop, and participate in game shows. It can also be used to communicate over long distances, perhaps to play interactive video games with someone halfway across the continent. Some visionaries see the revolution as the return of one-on-one communication like that of a town meeting. In any case, it is almost certain that satellite television will continue to proliferate in upcoming years.
Manufacturers will continue to make smaller and less costly satellite dishes. Recently, for instance, 18-inch (45.7-centimeter) diameter dishes have been introduced into the market in Japan, Europe, and the United States. These dishes are small enough to fit on a windowsill or a porch railing. Manufacturers are also working on producing a flat-plate dish for satellite signal reception.
Where To Learn More
Books
Baylin, Frank, and Amy Toner. Satellites Today. ConSol Network, Inc., 1984.
Clifford, Martin. The Complete Guide to Satellite TV. Tab Books, 1984.
Easton, Anthony T. The Home Satellite TV Book. Wideview Books, 1982.
Prentiss, Stan. Satellite Communications. Tab Books, 1987.
Sutphin, S. E. Understanding Satellite Television Reception. Prentice-Hall, 1986.
Traister, John E. Guide to Satellite Television Installation. Prentice-Hall, 1987.
Traister, Robert J. Build a Personal Earth Station for Worldwide Satellite TV Reception. Tab Books, 1985.
Periodicals
Booth, Stephen A. "Signals from Space," Popular Mechanics. April, 1992, p. 60.
Elrich, David. "Satellite TV: It's Worth a Closer Look," Home Mechanix. September, 1990, p. 78.
—Rose Secrest
A satellite dish is a parabolic television antenna that receives signals from communication satellites in orbit around the earth. Its sole function is to provide the television viewer with a wider variety of channels.
The first communications satellite—Echo I—was launched by the United States in 1960, transmitting telephone signals. In 1961 Relay began transmitting television signals, and in the same year Syncom established itself as the first geosynchronous satellite capable of transmitting signals to one particular section of the earth's surface continuously.
The rapid advances in communication satellite technology were not simultaneously matched by advances in satellite dish use and technology. Television broadcasting began with individual stations that could only serve a limited area. Television networks had to provide their affiliate stations with recordings of programs if they wished to provide nationwide service. Satellite television was not widely available until the 1970s, when cable television stations equipped with satellite dishes received signals that were then sent to subscribers by coaxial cable. By 1976, there were 130 satellite dishes owned by cable companies, and by 1980, every cable television station had at least one satellite dish.
About that time personal satellite dish earth stations were selling for approximately $35,000 per unit. Taylor Howard, an employee at Stanford University who was well-versed in the usefulness of satellites as relayers of data, is credited with designing the first satellite dish for personal use. Howard's dish, which was placed into operation on September 14, 1976, was made of aluminum mesh and was about 16 feet (5 meters) wide. By 1980,5,000 satellite dishes had been purchased for home use. In 1984 alone 500,000 were installed. Recent reports state that there are 3.7 million owners of home satellite dishes worldwide, and the number will continue to grow.
A typical commercial satellite dish of the 1970s was made of heavy fiberglass, and the dish itself, at its smallest size, had a diameter of about ten feet (three meters). Since then, satellite dish design has shifted toward light-weight, aluminum mesh dishes (similar to Howard's homemade dish), some of which are inexpensive and small (three feet, or one meter, in diameter is typical), with many sections (petals) that can be easily assembled. England, Japan, and Germany, have led the way with direct broadcast TV, which sends signals directly to the viewer's dish, but the United States has yet to do so. This trend would yield smaller, more affordable satellite dishes and regulated satellite programming.
Raw Materials
The basic satellite dish consists of the following materials:
A parabolic reflector made of fiberglass or metal, usually aluminum, with a protruding steel feed horn and amplifier in its middle.
A steel actuator that enables the dish to receive signals from more than one satellite.
A metal (usually aluminum) shroud measuring about 6 to 18 inches (15 to 45 centimeters) in height. It is installed on the dish's circumference perpendicularly to reduce side interference.
Cables, most likely made from vinyl tubing and copper wiring.
The Manufacturing Process
1 To make fiberglass suitable for dish manufacture, a sheet molding compound mixture that includes reflective metallic material and ultraviolet scattering compositions is mixed with resin, calcium carbonate, and a catalyst cure. This mixture forms a paste that is poured onto a sheet of polyethylene film that has fiberglass added in chopped form. The result is a sheet layered with the compound paste, fiberglass, and the polyethylene film.
2 This sheet is then pressed at 89 degrees Fahrenheit (30 degrees Celsius) to mature. To shape the sheet into the desired parabolic shape, it is pressed at high pressure (of 1,400-2,200 metric tons). The dish is then trimmed, cooled, and painted. After the paint has dried, the dish is packed for shipment in sturdy boxes.
3 For metallic dishes, the common metal of choice is aluminum. This type of dish can be assembled in sections called petals, or all at once. An aluminum plate is perforated with a punching die, creating tiny holes. The size of these holes are contingent on the manufacturer's preference. Larger holes mean greater loss of the signal, so fairly small holes are selected. Another factor in the selection of hole size is the power of the broadcasting satellite. Newer, more powerful satellites require a hole size that is approximately half that required for older, less powerful satellites. The newly perforated aluminum plate is then heated, stretched over a mold, cooled, and trimmed. A paint powder coating for protection is then applied using an electrostatic charge, in which the paint is given an opposite electrical charge from the plate. The dish or petal is then heated to melt the powder and seal the paint on. The petals are usually sealed together with ribs in the factory.
4 Mesh petals are made from aluminum that is extruded—forced into a die of the proper shape. They are usually joined together on site by sliding them into aluminum ribs that attach to the hub and then securing them with metal pins.
Installation
5 All dishes, when complete, will have the necessary equipment (the feed horn, the amplifier, etc.) installed in the factory. When the dish has been set up at the local dealer, it is transported to the site location on a open trailer. Satellite dishes can be installed either by professionals or by the purchaser, with assistance from the retailer if necessary. The method selected depends upon the size of the dish and the mechanical expertise of the purchaser.
6 An installation site reasonably clear of obstructions not more than 246 feet (75 meters) from the house is selected. Site selection is also contingent on local building codes and the possibility of microwave interference from radio and television towers in the vicinity. Once a site is selected, the base must be installed first. The base of most satellite dishes consists of a concrete foundation that extends below the frost line. A clayey soil is excellent, while sandy or rocky soil requires more concrete. A base tube filled with concrete is then set into the concrete foundation.
Some satellite dishes require a slab mount installation, a method considered to be more stable than typical base construction. In some cases, slab mount installation is necessary since the site selected for the placement of the satellite dish is unstable. The slab is generally 1.6 feet (.5 meter) square and 3.2 feet (1 meter) deep. Soil is excavated to the proper depth and the concrete is poured. A triangular steel mount fixture is then embedded into the concrete.
7 Next, the pedestal is attached to either the base tube or the triangular steel mount fixture. The elevation arm is then attached to the pedestal.
Alignment
8 The mounted satellite dish must be aligned in order to point toward the satellite. The angle at which the dish is eventually situated will vary according to which satellite is selected and at what latitude the dish is located. Coaxial cables connect the satellite to the receiver that is located in the house near the television. A trench must be dug for these cables, which are placed into a pipe before being buried.
Quality Control
Satellite dishes for consumer use are not usually required to undergo rigorous tests with set standards, but some parameters are generally met. For example, so that the microwaves are received properly, the surface of the dish should be as smooth as possible and its parabolic shape should be exact. It must also be composed at least partially of metal, otherwise the microwaves will not reflect. If the dish is either mesh or perforated aluminum, the holes must be relatively tiny to minimize loss. Dish size is important; it should match that appropriate to the latitude. The mount should be sturdy, and the dish aligned properly for maximum reception.
Members and joints are tested and compared to the American Steel Construction Institute or the American Aluminum Association methods rules, whichever apply. The satellite dish should be built to withstand high winds, snow, ice, rain, and extreme temperatures.
After the dish is installed, the owner is generally responsible for cleaning it twice a year, more if necessary, tightening and lubricating all bolts once a year, and trimming obstructive weeds and trees from around it. In rare occasions, the owner must adjust the alignment to correct bad reception.
The Future
Satellite dishes will become ubiquitous in upcoming years. More communication satellites will certainly be launched, and the growth explosion in individual satellite dish ownership will continue. One factor that should affect home satellite dish ownership in the near future is the switchover to more powerful satellites that will transmit signals in the K band (12 GHz). Because most of the present satellite dishes accept signals in the C band (3.7 to 4.2 GHz), owners of C band satellite dishes will have to convert them to K band. Researchers and designers are contemplating even smaller dishes that could be placed on a rooftop or outside a window and still function as well as the larger satellite dishes of today.
Some experts see the growth of satellite television as a revolution that is less concerned with crystal clear images of old sitcoms than with the possibilities of two-way communication that universal dish ownership would promote. Satellite television will be used to pay bills, shop, and participate in game shows. It can also be used to communicate over long distances, perhaps to play interactive video games with someone halfway across the continent. Some visionaries see the revolution as the return of one-on-one communication like that of a town meeting. In any case, it is almost certain that satellite television will continue to proliferate in upcoming years.
Manufacturers will continue to make smaller and less costly satellite dishes. Recently, for instance, 18-inch (45.7-centimeter) diameter dishes have been introduced into the market in Japan, Europe, and the United States. These dishes are small enough to fit on a windowsill or a porch railing. Manufacturers are also working on producing a flat-plate dish for satellite signal reception.
Where To Learn More
Books
Baylin, Frank, and Amy Toner. Satellites Today. ConSol Network, Inc., 1984.
Clifford, Martin. The Complete Guide to Satellite TV. Tab Books, 1984.
Easton, Anthony T. The Home Satellite TV Book. Wideview Books, 1982.
Prentiss, Stan. Satellite Communications. Tab Books, 1987.
Sutphin, S. E. Understanding Satellite Television Reception. Prentice-Hall, 1986.
Traister, John E. Guide to Satellite Television Installation. Prentice-Hall, 1987.
Traister, Robert J. Build a Personal Earth Station for Worldwide Satellite TV Reception. Tab Books, 1985.
Periodicals
Booth, Stephen A. "Signals from Space," Popular Mechanics. April, 1992, p. 60.
Elrich, David. "Satellite TV: It's Worth a Closer Look," Home Mechanix. September, 1990, p. 78.
—Rose Secrest
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