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Huge coverage
A satellite “sees” an area several thousand kilometres across. From Warsaw you can work Portugal, Scandinavia or the Balkans — without ionospheric propagation.
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Curiosities · space
Satellite communication
Over our heads, at altitudes from a few hundred to almost 36,000 kilometres, a fleet of satellites built and maintained by radio amateurs themselves is in orbit. Each of them is a repeater in space: you send a signal up, the satellite immediately turns it back down to Earth — and suddenly, with a handheld beam antenna, you’re talking to a station thousands of kilometres away. Your first contact doesn’t require a fortune or a huge mast.
LEO · low‑Earth‑orbit satellites
ISS · Space Station
QO-100 · geostationary
FM · SSB · CW · digital
What it’s about
A repeater — just in orbit
It works the same as a terrestrial repeater — only the “high point” is a satellite racing over the horizon at nearly 28,000 km/h. That speed and altitude give a range you’ll never achieve from the ground.
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Modest kit
For the simple FM birds a dual‑band handheld and a handheld directional antenna are enough. The rest is knowledge: when and where to look in the sky.
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Short window
A low satellite is in range for only 5–15 minutes per pass. It’s a sprint: you have to work quickly, efficiently and think on your feet — that’s why it’s so addictive.
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Real space
Through the very same transponder as you, operators from across the continent are talking, and through the ISS you sometimes hear the astronauts themselves. It’s a tangible link to orbit.
How it all started
Over 60 years of amateurs in space
Radio amateurs have been in space almost since the dawn of the satellite age — and they’re still there today.
From OSCAR to today
- 1961 — OSCAR 1. Just four years after Sputnik, radio amateurs launched their own satellite. It transmitted a simple “HI HI” in Morse and weighed a few kilograms. The acronym OSCAR stands for Orbiting Satellite Carrying Amateur Radio.
- Decades of development. Successive satellites of the OSCAR series (AO, FO, RS…) introduced linear transponders, intercontinental contacts and experiments that later made their way into ‘big’ space technology.
- The cubesat era. Today dozens of tiny satellites the size of a shoebox carry amateur transponders and telemetry. They’re built by young people, universities and clubs from all over the world.
- 2019 — QO-100. The first amateur transponder in geostationary orbit — available around the clock over one third of the globe. A breakthrough previous generations could only dream of.
Who you’ll hear
Four types of satellites
They differ by orbit, transponder type and difficulty. To start with, the “FM birds” and the ISS are best.
FM satellites (“birds”)
LEO · 200–800 kmEASY
A flying FM repeater: one QSO at a time, like on a terrestrial repeater. Ideal for your first contact — a dual‑band handheld and a directional antenna will do. You just have to “shout over” the crowd, because the whole region picks the same transponder.
| Satellite | Downlink / Uplink |
|---|---|
| SO-50 | 435 MHz ↓ / 145 MHz ↑ · FM (tone 67.0) |
| ISS (FM repeater) | 437.800 ↓ / 145.990 ↑ · tone 67.0 |
| Transponder type | cross‑band U/V — listen on 70 cm, transmit on 2 m |
Linear transponders
LEO · SSB / CWMEDIUM
Instead of a single FM channel — a whole slice of spectrum that fits many QSOs at once in SSB and CW. Quieter, more civilised and further than FM, but you have to retune the receiver continuously to chase the drifting frequency (Doppler effect).
| Parameter | Value |
|---|---|
| RS-44 (downlink) | 435.610–435.670 MHz |
| RS-44 (uplink) | 145.935–145.995 MHz |
| Modes | SSB (USB) and CW · mode V/U |
ISS — the Space Station
LEO · ≈ 420 kmEASY
The largest and brightest “satellite” in the sky. Besides the FM repeater it offers an APRS digipeater (position packets via space!) and occasional SSTV image transmissions, which you can receive even with a plain handheld and a phone with an app.
| Service | Frequency |
|---|---|
| FM repeater (voice) | 437.800 ↓ / 145.990 ↑ (tone 67.0) |
| APRS (packet) | 145.825 MHz · simplex |
| SSTV (images, occasionally) | 145.800 MHz · FM |
QO-100 — geostationary
GEO · 35,786 kmKIT
It stays fixed over Africa and is available 24 hours a day — from Brazil to Thailand. It doesn’t move, you don’t have to track it. The price of that convenience is microwave kit: a satellite dish, a 10 GHz converter and a 2.4 GHz transmit chain.
| Narrowband transponder | Frequency |
|---|---|
| Downlink (reception) | 10,489.55–10,489.80 MHz (13 cm ↦ 3 cm) |
| Uplink (transmitting) | 2,400.05–2,400.30 MHz (13 cm) |
| Modes | SSB · CW · narrowband digital |
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Shorthand on frequencies: ↓ downlink is the signal from the satellite to you (you listen), ↑ uplink is your signal up (you transmit). Mode U/V means uplink on UHF (70 cm) and downlink on VHF (2 m); V/U — the other way round. Always check current, exact frequencies and satellite status in the AMSAT listings — they are sometimes switched off and back on.
Physics in a nutshell
How it really works
Three ideas are enough to understand why satellite contacts work the way they do: cross-band, the Doppler effect and the pass window.
Uplink, downlink and the Doppler effect
- Two different bands at once. The satellite receives on one band and transmits on another (e.g. receives on 2 m, transmits on 70 cm). Thanks to this, it can listen and speak at the same time — and your radio must operate in satellite mode / full duplex.
- The Doppler effect. The satellite rushes towards you, then away — and the frequency you hear shifts during the pass (on 70 cm by as much as ±10 kHz). At the start of the pass you tune a bit higher, at the end lower. Radio control software does it for you.
- Pass window. The satellite is in range from rise (AOS) to set (LOS) above the horizon — usually a few to a dozen minutes. The higher it passes overhead (greater elevation), the stronger and longer the signal.
- Polarisation and “fading”. A tumbling satellite causes signal fades. A gentle twist of the antenna in your hand, or an antenna with circular polarisation, can pull a station out of the noise.
✓
Golden rule: correct Doppler primarily on the uplink (where you transmit), and trim the downlink by ear, ‘chasing’ your own signal. In practice you set a few memory pairs in the radio, or hand control over to the tracking program — and you focus on the conversation.
What to use
Gear — from handheld to dish
The barrier to entry is surprisingly low. You only expand later — and only if you catch the bug.
Setup for LEO satellites (FM and linear)
- Dual-band radio with satellite mode — supporting simultaneous receive and transmit on 2 m and 70 cm (full duplex). Advanced users run a transceiver with a CAT frequency-control port.
- Handheld directional antenna — a light dual-band Yagi (like an “Arrow” or “Elk”), which you aim at the satellite like binoculars. This makes the biggest difference — far more than transmitter power.
- Headphones — to pick out a weak station in the noise and to avoid your own speaker drowning out the downlink.
- Optional rotor + mast — a fixed antenna automatically steered in azimuth and elevation, for those who want to operate from home without going outside.
QO-100 setup (geostationary)
- 60–100 cm satellite dish — an ordinary TV ‘dish’, aligned once towards the satellite. Nothing moves, because the satellite sits in one spot.
- 10 GHz converter (LNB) — brings the received 3 cm signal down to a band your receiver or SDR can hear. Often stabilised by an external reference.
- 2.4 GHz transmit chain — a transmitter and a small directional antenna for the uplink in the 13 cm band.
- SDR or transceiver — for receiving and transmitting SSB/CW. Many operators listen to QO-100 online via a public WebSDR before building their own station.
Start with listening — for free
Before you buy anything, you can listen. The QO-100 downlink is available via online WebSDR receivers — open a page in your browser and hear live QSOs from across a whole hemisphere. You can receive LEO satellites with an ordinary handheld and the antenna pointed at the sky, even just as a trial.
For listening you don’t need any licence. Only transmitting requires an operator’s certificate and a radio licence (exam at UKE — the Polish Office of Electronic Communications) — more below.
When and where
Tracking passes
A LEO satellite is over you only briefly and a few times a day. You need to know when and which part of the sky to look at — luckily software does this for us.
How to predict a pass
- Orbital elements (TLE). These are two lines of numbers describing a satellite’s orbit, published e.g. by Celestrak. The program loads the current TLE and works out where and when the satellite will pass over your locator.
- Computer program — e.g. Gpredict or SatPC32. Shows a pass map, azimuth and elevation, and can even control the radio and rotor, correcting Doppler in real time.
- Phone app — Look4Sat, ISS Detector and the like. They give the pass time, direction and height above the horizon — ideal for hand-held work in the field.
- Look for high passes. A pass peaking at 40–80° will give a strong, long signal. At 5–10° above the horizon the satellite will barely graze your coverage and get lost in obstructions.
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Worth knowing: SatNOGS is a global, open network of amateur ground stations that automatically listen to satellites and share recordings. Without your own antenna, you can use it to see and hear what satellites ‘transmit’ over different points on Earth.
Step by step
First QSO via satellite
The easiest way is to start with an FM satellite or the ISS repeater. Here’s the whole run — from plan to ‘73’.
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Pick an easy target
Start with an FM satellite (e.g. SO-50) or the FM repeater on the ISS. One channel, one QSO at a time — the fewest things that can go wrong.
2
Find a pass
In the app, check the next high pass over your QTH: the time, the direction of rise and set, and the maximum elevation.
“tomorrow 20:14, from NW to SE, elevation 62°”3
Set up the radio
Load the uplink/downlink frequencies with Doppler correction (a few memory pairs) and the correct CTCSS tone. Enable satellite mode / full duplex so you can hear yourself on the downlink.
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Catch your own signal
Aim the antenna at the rising satellite and tune the downlink until you hear your own voice in it. That means you’re getting through the transponder — you’re in space.
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Call briefly
On a crowded FM pass the QSO is a rapid exchange: callsign and locator. No chit-chat — there’s a queue waiting and the window is closing.
“SQ5CBA, KO02, who’s copying?”6
Exchange and thank
Confirm the other station’s callsign and your locator, get theirs — and clear the frequency for the next stations. QSO complete!
“thanks for the sat, 73! SQ5CBA”
✓
Tip: for the first time it’s easiest to work just by monitoring your own signal by ear, and to hold the antenna in your hand and slowly rotate it, hunting for the strongest spot. Record the downlink with your phone — after the pass you’ll calmly pick out the callsigns you missed live.
Not just talking
What else is possible
Amateur satellites aren’t only about voice QSOs — there’s a whole world of experiments here.
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APRS via satellite
Via the digipeater on the ISS (145.825 MHz) you can send a position packet that is digipeated from orbit and reaches the terrestrial network. Your track on the map — via satellite.
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SSTV images
The ISS periodically transmits pictures on 145.800 MHz using slow-scan TV (SSTV). You can receive them with a handheld and a phone app, and there are often certificates for received images.
☁
Weather satellites
This isn’t an amateur band, but a related pastime: around 137 MHz you can receive cloud images from NOAA and Meteor weather satellites on receive only. Great tracking practice.
☰
CubeSat telemetry
Dozens of student satellites transmit data about their status. By receiving and reporting it you genuinely help the mission teams — citizen science straight from orbit.
Cheat sheet
Mini satellite glossary
- LEO
- low Earth orbit (a few hundred kilometres) — the satellite passes quickly
- GEO
- geostationary orbit (35,786 km) — the satellite appears to ‘hang’ motionless, like QO-100
- Uplink ↑
- the signal you transmit up to the satellite
- Downlink ↓
- the signal the satellite transmits down to you
- Transponder
- the satellite’s receiver–transmitter: FM (single channel) or linear (a slice of spectrum)
- Mode U/V
- uplink on UHF (70 cm), downlink on VHF (2 m); V/U — the other way round
- Doppler
- frequency shift due to the satellite’s motion — you need to retune continuously
- AOS / LOS
- satellite rise / set above the horizon — the start and end of the contact window
- Elevation
- the satellite’s height above the horizon in degrees; the higher, the stronger
- TLE
- two-line element set — data for predicting passes
- Footprint
- the area on Earth from which the satellite is visible at a given moment
- Locator
- Maidenhead grid (e.g. KO02) — your position exchanged in a QSO
Before you go on the air
Listening is free, transmitting under licence
Anyone can listen to satellites — straight away, with no formalities. To transmit (including via satellite), you need an operator’s certificate and a radio licence from the exam at UKE (the Polish Office of Electronic Communications). Start with listening and learning the code — CW will come in handy on weak signals from orbit.