Radio Equipment: Antennas, Transmitters, Power, and Software

Antennas and FM Radio Equipment

FM radio works on a system of frequencies where different broadcasters can reserve and use specific ones. The sound of the music or other programming is used to modulate a carrier wave of the specific frequency, then broadcast.

Every legitimate commercial FM station conducts periodic audience measurements or’sweeps’ to see how many people are listening to it. These are done with devices that insert almost-inaudible tones into the audio and then portable people meters to detect them.


An antenna is a transmitter/receiver that transforms electromagnetic waves into an electric current and then back again to create radio signals. Transmitter antennas handle high power and need to direct their radiated signal in the desired direction. Receiver antennas, on the other hand, require very low power and can accept signals from any direction. There are four characteristics of FM antennas that are important: directionality, gain, bandwidth and polarization.

A high-quality FM receiving antenna will give you excellent reception even in the middle of a large city. A good choice is a bidirectional dipole, which has decent gain for an indoor FM antenna.

For outdoor FM reception, there are many different types of antennas to choose from. Yagis, collinears and log periodics are all high-efficiency antennas that can provide excellent results for suburban and rural installations. These antennas are usually mounted high on a mast, so they must be properly positioned to avoid interference. It’s recommended to test the performance of an FM antenna before permanently installing it.


A transmitter converts alternating current to radio frequencies and transmits them through an antenna. The resulting radio waves are then picked up by a receiver and transformed into sound. The type of transmitter used determines the range of audio that can be transmitted and its quality.

Low-power FM transmitters can be used in homes, offices, and public spaces to play music from mobile devices. They can also be used to broadcast a message or podcast to an audience in close proximity.

In order to use an FM transmitter properly, you must find a frequency that is free of interference. This is easy to do in rural areas where there isn’t much competition for radio frequencies, but it’s a lot harder in crowded cities.

FM transmitters can also be found in fitness centers to play music over the gym’s workout equipment. This allows exercisers to listen to music on their personal headphones or earbuds without interrupting others with loud stereo sounds.


The equipment of an FM radio station uses large amounts of power. This is because the transmitters need to be powerful enough to broadcast signals over a significant distance, and the studio equipment also needs considerable wattage to handle the audio signals. Some stations require hundreds of kW or more.

The audio signal that comes from the studio is used to modulate (code) a carrier wave of a specific frequency. This wave is then broadcast to the audience. The range of the broadcast is determined by the RF power, the antenna gain, and the height of the transmitter and antenna.

An FM transmitter combiner does a bit of magic, combining multiple RF signals that are close together on the frequency spectrum into one signal that is transmitted from the FM antenna array. These units also contain filters to ensure each transmitter doesn’t spew out RF outside of its expected range. This increases the efficiency of the FM transmission.


FM is a broadcast band that can be used to transmit audio programming such as music, news and conversations. It does this by modulating a signal onto an existing audio line. Then the transmitter converts that signal into an electrical current that represents sound.

Modern radio stations are run by automation software to either play audio on their own without a human or to assist a live DJ/personality in running the station. Radio automation software solutions typically include a media database that stores attributes on audio files (such as the artist, title, and track number) and a browser for those files with search capabilities.

Some radio stations also use a separate piece of software to control and play back commercials at future pre-defined times. This allows them to maintain detailed logs of their programs for compliance with regulators and to demonstrate to advertisers that their ads are being aired. The open source software Rivendell is one such solution that has been embraced by smaller independent stations.

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