How Does an FM Radio Transmitter Work?

An FM radio transmitter is a wonderful tool for those interested in electromagnetism. In the world of 3G telephones and Wi-Fi network services, many people no longer listen to radio. However, it is this radio signal which is instrumental in the functioning of our modern day high speed Internet and mobile technology. The mechanism behind the working of a radio transmitter depends on an oscillator that produces carrier signal on a particular frequency. When the particular signal needs to be controlled, then a voltage modulator is used. In the absence of the modulator, the frequency is transmitted at the pre-defined frequency signal. The FM signal is then transmitted into the outer space through an antenna.

This article will highlight the mechanism of how the circuit of an FM transmitter works. The mechanism can be divided broadly into two categories, namely origination and transmission.


A signal first starts out its journey as sine waves. When its journey begins, it has no information encrypted in it. Information gets inscribed when it receives electromagnetic signals. These electromagnetic waves are stronger than mechanical waves because electro-magnetic waves can travel at the speed of light through a vacuum. FM stands for frequency modulation, which means that it can reproduce the sound from the source of origin. This is the reason why FM stations can play very high quality music channels.

Transmission & Reception

The process of transmitting radio signal occurs when sound is transformed into sine waves and transmitted. The lengths of the sine waves are altered using frequency modification in order to transmit them to FM receivers. Electrical signals are pushed through the broadcasting antenna at a rate that closely relates to the carrier frequency. This movement creates an electromagnetic field which radiates electromagnetic waves. These carrier waves, which are so created, are sent out at a frequency which can be captured by the antenna of the individual receiver antenna. The antenna no doubt receives a lot of radio signal. Using a tuner, the desired channel can be tuned or the desired radio station frequency fixed. The detector in the radio then transforms the sine wave of that radio station into sound, and the amplifier increases its volume. A radio station that has a more powerful tower is likely to have better coverage.

There are instances when we fail to hear a radio station. It is due to the transmission failure caused by short waves. Short waves are transmitted in a straight line off of the earth’s crust. Since the earth is round, the signal gets interrupted in its way. Oftentimes, high mountain ranges hamper radio transmission.

However, nowadays there are many new technologies which have come into being. Now radios are available with built-in antennas and also over the Internet. From simple radio signal, these waves are instrumental in the functioning of navigation satellites to GPS network. Ironically, the technology needed to build and transmit such powerful signals is relatively very cheap. Radio transmission technology is the perfect example of value for money combined with advanced technology.