The one thing that matters most
Before any shopping list: antenna position beats every other decision combined.
1090 MHz is line-of-sight. A £150 receiver with the antenna indoors on a windowsill will be comprehensively beaten by a £25 dongle with a basic antenna mounted clear of the roofline. Height and an unobstructed horizon are the whole game. Walls, roof tiles, foil-backed insulation and wet trees all absorb the signal aggressively.
If you can only do one thing well, get the antenna high and outside. Everything below is optimisation on top of that.
Every doubling of usable antenna height meaningfully extends your horizon. Moving from a ground-floor window to a chimney mount routinely doubles or triples aircraft counts — far more than any upgrade to the receiver itself.
The receiver
The standard starting point is an RTL-SDR dongle — a USB software-defined radio originally designed as a TV tuner, built around the RTL2832U chip. Hobbyists discovered years ago that it could be repurposed to receive almost anything, including 1090 MHz.
Three tiers, in ascending order of cost:
- Generic RTL-SDR — the cheapest option. Works, but has no filtering, so strong nearby transmitters (mobile masts, broadcast sites) can swamp it.
- ADS-B-specific stick — the sensible default. These have a 1090 MHz filter and a low-noise amplifier built in, which makes a substantial difference in a noisy RF environment such as a town.
- Dedicated SDR hardware — better dynamic range and sensitivity, at several times the price. Worth it only once the antenna and cable are already excellent.
For a first build, the middle option is the right call. The premium over a generic dongle is small and the filtering earns it back immediately.
The antenna
1090 MHz has a wavelength of about 27.5 cm, which is why purpose-built ADS-B antennas are so conveniently small. Options, roughly in order:
The stock whip
Whatever came in the box. Fine for confirming everything works on day one, and not much more. Use it to prove the software, then replace it.
A quarter-wave groundplane
A vertical element about 6.9 cm long with four radials. This is the classic homebrew build — people make them from coat hanger wire and an SO-239 socket for the price of a coffee, and they perform respectably.
A commercial collinear
A tuned vertical collinear in a weatherproof tube, typically claiming 5–7 dBi. These concentrate the pattern towards the horizon, which is exactly where distant aircraft are. This is the usual end point for a serious home setup.
High-gain antennas squash the radiation pattern flat. Superb for reaching aircraft 200 miles away, worse for the airliner passing directly overhead at 38,000 ft, which ends up in the null above the antenna. If you live under an approach path, moderate gain often gives a more useful picture.
Cable — where the signal quietly dies
This is the most commonly neglected component. Coaxial loss rises sharply with frequency, and 1090 MHz is high enough that ordinary thin coax is genuinely expensive in decibels.
| Cable | Character at 1090 MHz | Verdict |
|---|---|---|
| RG-174 / thin patch leads | Very lossy | Only for very short runs — under a metre |
| RG-58 | Lossy | Tolerable for a couple of metres, poor beyond that |
| LMR-240 or equivalent | Moderate loss | Good for typical 5–10 m runs |
| LMR-400 or equivalent | Low loss | Thick and stiff, but the right answer for long runs |
A long run of cheap coax can throw away more signal than a better antenna ever recovers. The standard workaround is to keep the cable short by putting the receiver near the antenna and running network over the distance instead — Ethernet or Wi-Fi carries data without caring how far it goes.
The computer
A Raspberry Pi is the conventional host: low power, silent, and happy running unattended for years. A Pi Zero 2 W is sufficient for a single receiver; a Pi 4 or 5 gives headroom if you want to run several decoders and a local map.
Any Linux machine works, and so does a PC — but a dedicated low-power box you can leave switched on is much more satisfying than remembering to start software each time.
Use a genuinely adequate power supply. Undervoltage is the single most common cause of a receiver that "randomly stops working" — the symptoms look like a software fault and are not.
The software
Decoding is handled by one of a family of related open-source programs descended from the original
dump1090:
- dump1090 and its forks — the classic decoder, still widely used.
- readsb — a modern, actively developed successor, more efficient and the usual recommendation for new builds.
- tar1090 — a web map front-end that gives you a local browser view of your own traffic.
- graphs1090 — long-run statistics on message rates, range and system health. The quickest way to tell whether a change actually improved anything.
Several feeder networks publish ready-made SD card images that install a decoder, a local map and their feeding client in one step. If you intend to share data anyway, starting from one of those images is the path of least resistance.
What it costs
| Build | Rough outlay | What you get |
|---|---|---|
| Minimum viable | £40–60 | Generic dongle, stock or homebrew antenna, a Pi you already own. Proves the concept. |
| Sensible starter | £100–150 | Filtered ADS-B stick, commercial antenna, decent coax, dedicated Pi and PSU. Genuinely good coverage. |
| Enthusiast | £250+ | Better SDR, external LNA, high-grade cable, proper mast mounting and weatherproofing. |
The jump from the first row to the second is very large in results. The jump from the second to the third is usually modest unless your antenna is already mounted well.
Getting more range
Once it is running, the improvements worth making, in order:
- Raise the antenna and clear the horizon. Still the biggest single lever.
- Shorten or upgrade the coax. Free decibels if the run is currently long and cheap.
- Add a 1090 MHz filter if you are near broadcast or mobile transmitters and the receiver is being desensitised.
- Add an LNA at the antenna — amplifying before the cable loss rather than after it.
- Tune the gain setting in software. Maximum gain is rarely optimal; too much overloads the receiver and message rates fall. Step through settings and watch the statistics.
Community coverage exists because individuals run receivers and share what they pick up. If you get a site running, feeding it into a network fills in gaps that no single receiver could cover — and it is how services like this one see anything at all.
Feed FlightBank and your API access is free for as long as your receiver is online — no subscription, no card. It runs alongside PiAware, ADS-B Exchange or any other feeder you already have, reading from the same decoder rather than competing with it. Works with dump1090-fa, dump1090-mutability and readsb.
A note on rules
ADS-B is an unencrypted broadcast intended to be received, and receiving it as a hobby is widespread and well established. Regulations covering radio reception nonetheless differ between countries and change over time, so check the current position with your national regulator rather than assuming. Whatever you build, the data is for interest — it is never a substitute for official information, and must not be used operationally.