Choosing an RTL-SDR stick and antennas
All RTL-SDR sticks share the same Realtek RTL2832U chip that turns radio into samples. What sets them apart is the tuner chip in front of it, the crystal, and the extras around them. For this app, the tuner decides how much works.
The tuner: what the app supports
| Tuner | Found in | In the app |
|---|---|---|
| R820T / R820T2 | RTL-SDR Blog V3, Nooelec NESDR, most generic sticks | Full support; HF by direct sampling |
| R828D | RTL-SDR Blog V4 | Full support; HF through the built-in upconverter |
| R828S | RTL-SDR Blog V4L | Basic support: tuning from 24 MHz, no HF yet |
| E4000, FC0012, FC0013, FC2580 | Older and rare sticks | Basic mode only: spectrum and recording, no tuning or gain |
With a supported tuner the app tunes from 24 MHz to about 1.7 GHz, plus HF below that by one of the HF paths.
Blog V3 or V4
Both come from RTL-SDR Blog, have a TCXO (frequency within about 1 ppm, so no calibration), a 4.5 V bias-T for powering an LNA or active antenna, and a metal case that helps with noise. The difference is HF. The V4 has a built-in upconverter, so shortwave goes through the tuner with its gain and filtering; it also switches its own notch filters against FM and DAB broadcast. The V3 reaches HF by direct sampling, which works but is noisier and easier to overload. For VHF and UHF the two are close.
RTL-SDR Blog has ended the V4 line and now sells a V4L (Lite) with an R828S tuner. The app has basic support for it: it tunes from 24 MHz up as on other sticks, but HF on the V4L is not supported yet (no upconverter, no direct sampling). More will follow once owners report how theirs behaves. The V3 is still sold, also as the V3C with a USB-C socket.
Cheap unbranded “TV dongles” with an R820T2 also work in the app. They usually drift more (no TCXO, so use Calibrate), run hot, have no bias-T and use a small MCX socket instead of SMA.
Antennas by what you want to hear
| You want | Start with | Then |
|---|---|---|
| FM broadcast, airband, ham VHF/UHF, PMR | The telescopic dipole from the kit, extended to a quarter wave per arm | A discone outdoors, as high as you can |
| Aircraft (ADS-B, 1090 MHz) | The kit dipole with short arms (about 7 cm each) | A dedicated 1090 MHz antenna by a window or outside |
| Weather satellites (137 MHz) | The kit dipole as a V, arms about 53 cm, opened to 120°, lying flat | A QFH or turnstile antenna |
| Shortwave (HF) | A longwire through a 9:1 unun | An active or passive loop if you are in town |
A dipole arm should be about a quarter wavelength long: in centimetres, roughly 7100 divided by the frequency in MHz. That gives about 49 cm at 145 MHz and about 16 cm at 446 MHz.
Filters, LNA and cables
- An FM broadcast stop filter (88–108 MHz) if strong FM stations overload the stick when you listen elsewhere. The V4 switches its own notch, so it needs one less often.
- An LNA only when you have a long or lossy coax run: put it at the antenna end and power it with the stick’s bias-T. Next to strong transmitters it makes overload worse, not better.
- A USB extension to move the stick away from the computer, and clip-on ferrites on the leads.
- A USB OTG adapter for an Android phone, plus a powered hub if the phone cannot supply the stick.
- Adapters to SMA male, because many antennas end in BNC, SO-239 or F connectors. See the adapters guide.
Every product on the gear pages is tagged ATS Mini, RTL-SDR or both. The items above are on the RTL-SDR receiver versions, RTL-SDR antennas and filters and accessories pages.
Recommended gear
- RTL-SDR Blog V3 with dipole kitReceiverA tuner the app fully supports, a TCXO, a bias-T and the dipole kit in one box.
- RTL-SDR Blog multipurpose dipole antenna kitAntennaThe kit’s telescopic dipole covers most of VHF and UHF; this is the same set sold on its own.
- SignalPlus D3000 discone antennaAntennaA discone hears everything from 25 MHz up without retuning: the antenna for a scanner on the roof.
- RTL-SDR Blog wideband LNA (V2)AntennaAn LNA at the antenna end makes up for a long coax run, powered by the stick’s bias-T.