What Equipment Is Needed for FM Broadcasting?
FM broadcasting takes two chains of equipment. First is an audio chain that captures and shapes sound: a microphone, a mixer, headphones, and an audio processor. Second is a radio-frequency (RF) chain that puts that sound on the air: an FM transmitter, a feedline, and an antenna. In the United States there is also a non-hardware requirement — a license from the FCC for anything beyond negligible transmit power — and for most stations that, not the gear, is the hard part.
The audio chain: everything before the transmitter
- Microphone. FM studios overwhelmingly use dynamic microphones with a cardioid pickup pattern, because a cardioid picks up the voice in front of it while rejecting sound arriving from behind — a property Shure explains in its educational primer on microphone designs and polar patterns. Our guide to choosing a broadcast microphone covers specific picks.
- Mixer or console. The mixer combines microphones, music playout, phone callers, and remote guests into one program signal, and gives the host fader control over each.
- Headphones. Live radio is monitored on closed headphones, not speakers, because an open speaker in the same room as a live microphone feeds back.
- Audio processor. Between the mixer and the transmitter sits a processor that compresses and limits the signal. This keeps the station's loudness consistent and, critically, prevents overmodulation — pushing the transmitter beyond the frequency swing it is allowed to use.
The RF chain: everything after
- Transmitter (or exciter). This is the piece that actually performs frequency modulation — encoding the audio by varying the frequency of a carrier wave, the mechanism illustrated in PBS's interactive AM/FM explainer. In the U.S., FM carriers sit in the band between 88 and 108 MHz, per the HyperPhysics reference on radio broadcast signals, which also describes how stereo FM is carried.
- Feedline. Heavy coaxial cable carries the transmitter's output to the antenna. Longer runs lose more power, which is one reason transmitters are usually installed close to the antenna rather than in the studio.
- Antenna and mast. The antenna radiates the signal as electromagnetic waves — the same physical phenomenon NASA describes in its tour of the radio portion of the spectrum. For FM, antenna height matters enormously: the higher the antenna, the farther the signal reaches before the curve of the earth gets in the way.
If the studio and transmitter are in different places, stations also need a studio-to-transmitter link — a dedicated connection that carries the program audio to the transmitter site.
What internet-only stations skip
An internet station needs the entire audio chain — mic, mixer, headphones, processing — but replaces the whole RF chain with an encoder and a streaming server. That is a large difference in cost, complexity, and regulation, which is why we compare the two models directly in internet radio vs. FM radio. If you want to trace the full journey of a signal through both kinds of chain, see how a broadcast gets from the microphone to your speakers.
The equipment nobody sells: a license
No list of FM equipment is complete without saying plainly that in the U.S. you cannot legally connect a transmitter of any meaningful power to an antenna without FCC authorization. The gear above is freely available to buy; the frequency to use it on is not. For most beginners, the practical path is to build the audio chain, start streaming online, and treat FM as a possible later step.