What's an RTL-SDR dongle?
AntennaHead needs one small piece of hardware to actually receive radio: a USB stick called an RTL-SDR dongle. Here's what it is, what it looks like, and which one to buy if you don't have one yet.
A repurposed TV tuner
RTL-SDR dongles started life as cheap USB TV tuner sticks for watching over-the-air digital TV on a PC. In 2010, hobbyists found that the tuner chip inside — the Realtek RTL2832U — could be told to dump its raw radio samples straight over USB instead of decoding TV with them. That turned a $10–$30 TV stick into a general-purpose software-defined radio (SDR) receiver.
Receive-only
It digitizes a slice of radio spectrum and hands the raw samples to software over USB — it doesn't transmit anything.
All the tuning is software
The dongle itself does no demodulation. AntennaHead does the actual FM/AM/airband math on the samples it streams in.
Wide coverage
Roughly 500 kHz–1.7 GHz depending on the model — FM & AM broadcast, airband, NOAA weather radio, ham bands, and more.
What it looks like
Physically it's about the size of a USB flash drive, with a coax antenna connector on one end. It plugs directly into a USB port (a short extension cable helps keep it away from other electronics), with an antenna attached to the connector.
Which one to get
Generic RTL2832U TV-tuner sticks are still sold everywhere for a few dollars, but quality varies a lot: cheap crystals drift off-frequency, and there's little protection against static or strong nearby signals overloading the front end. We recommend a dongle actually designed for SDR use instead of a repurposed TV tuner.
RTL-SDR Blog V3
The dongle most SDR software — AntennaHead included — is built and tested against. Temperature-compensated crystal oscillator (TCXO) for a stable, accurate frequency lock, better ESD/static protection, an aluminum case for shielding, extended range down into HF, and a bias-tee for powering an external LNA.
What's in the box
It ships with a small telescopic whip antenna and SMA/MCX adapters — enough to get FM broadcast and airband working right away. A dipole or discone antenna later improves range on weaker signals.
Buy the RTL-SDR Blog V3 (rtl-sdr.com) →
Once you have one, plug it into a USB port on your Mac and see the AntennaHead page for a tour of the tuner, favorites and scanner UI.