Amateur radio satellite
Amateur-built satellites enabling free radio communication for licensed operators worldwide.
Amateur radio satellites are artificial satellites built and operated by licensed amateur radio operators, belonging to the Amateur-satellite service. They rely on amateur radio frequency bands to link amateur stations. Most of these satellites receive an OSCAR designation—short for Orbiting Satellite Carrying Amateur Radio—assigned by the organization AMSAT, which is why they are commonly called OSCARs. Licensed amateurs can use them at no cost for voice communications (FM and SSB) and data modes (AX.25, packet radio, APRS). As of now, more than 18 fully operational amateur radio satellites are in orbit, serving as repeaters, linear transponders, or store-and-forward digital relays.
The first amateur satellite, OSCAR 1, launched on December 12, 1961, just four years after Sputnik I. It was built to a specific shape and weight so it could replace a ballast weight on the launch vehicle. It was the first satellite ejected as a secondary payload (the main payload was Discoverer 36) and entered its own orbit. With no onboard propulsion, its orbit decayed quickly, and it lasted only 22 days. Still, it was an immediate success, with over 570 amateur operators in 28 countries sending observations to Project OSCAR.
OSCAR 10 used mostly off-the-shelf components, led by Jan King. Solar cells were bought in small batches from Radio Shack and tested for efficiency; the best were kept, and the rest returned. Before launch, the satellite was mounted on a private plane and flown several times to check performance and reliability, with special QSL cards issued to participants. After passing those tests, it was shipped to Kennedy Space Center and installed in the launch vehicle’s third stage. OSCAR 10 measured 1.35 meters tall, 2.0 meters wide, and weighed 140 kg at launch (90 kg after engine firings).
Other satellite programs include Iskra (Soviet Union, around 1982), JAS-1 (Fuji-OSCAR 12, Japan, 1986), RS (Soviet Union and Russia), and CubeSats. Es’hail 2 (QO-100) launched on November 15, 2018, into geostationary orbit covering from Brazil to Thailand. It carries a narrowband linear transponder (uplink 2400.050–2400.300 MHz, downlink 10489.550–10489.800 MHz) and a wideband digital transponder (uplink 2401.500–2409.500 MHz, downlink 10491.000–10499.000 MHz).
Early amateur satellites had telemetry beacons.
- First amateur satellite
- OSCAR 1
- Launch date of first
- December 12, 1961
- Number of fully operational satellites c
- over 18
- Countries that have constructed an oscar
- 30
- Example geostationary satellite
- Es'hail 2 / QO-100
- Launch date of es hail 2
- November 15, 2018
Lore & Background
The first amateur satellite, OSCAR 1, was launched on December 12, 1961, barely four years after Sputnik I. It was built to a specific shape and weight to replace a launch vehicle ballast weight, and was the first satellite ejected as a secondary payload to enter a separate orbit. It carried no propulsion, orbited for only 22 days, yet over 570 amateur radio operators in 28 countries forwarded observations to Project OSCAR. OSCAR 10, built largely from off-the-shelf components, was tested aboard a private plane before shipment to Kennedy Space Center; its dimensions were 1.35 m height, 2.0 m width, and 140 kg mass at launch (90 kg post engine firings). Other programs include Iskra (Soviet Union, circa 1982), JAS-1 (Japan, 1986), RS (Soviet Union and Russia), and CubeSats. Es'hail 2 / QO-100, launched November 15, 2018, is in geostationary orbit covering Brazil to Thailand, with narrowband and wideband digital transponders.
Reader's Guide
Amateur radio satellites have helped advance the science of satellite communications, notably through the launch of the first satellite voice transponder (OSCAR 3) and the development of advanced digital store-and-forward messaging transponder techniques. The Amateur Radio Satellite community actively builds satellites and finds launch opportunities; lists of functioning satellites need regular updating as new ones launch and older ones fail. AMSAT has not been actively involved in the launch and operation of most amateur satellites in the last two decades beyond allocating OSCAR numbers. These satellites support FM voice, SSB voice, and digital modes such as AX.25 packet radio and PSK-31. Doppler shift, caused by high orbital speed, requires frequency correction during passes; FM is more tolerant and easier to tune manually than SSB. Low Earth orbit FM satellites, known as 'FM LEOs' or 'FM Birds', act as repeaters usable with handheld transceivers, with passes typically under 15 minutes. Mode designators use paired letters (e.g., Mode A: 2 m uplink / 10 m downlink) based on IEEE radar frequency bands.
Did You Know?
- OSCAR 10's solar cells were bought in batches of 10 or 20 from Radio Shack and tested for efficiency.
- Es'hail 2 / QO-100 is in geostationary orbit covering from Brazil to Thailand.
- SuitSat, an obsolete Russian space suit with a transmitter, was officially known as AMSAT-OSCAR 54.
More in Amateur Radio 1-24
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