(eli5) Radio frequency span


Why do we have only 87.5-108 MHz on radio? What about those 0-87.4, and those over 108?

In: 3

88-108 Mhz is used for FM radio. Frequencies above and below that are used for other things. Some of those other things are mobile phones, baby monitors, air traffic control, ship to shore communication, emergency services, cordless phones, business radio communication, and lots more.

Radio frequencies are a public resource. Their use is controlled by most governments. It is illegal to broadcast on frequencies not assigned and licensed. (There are some frequency ranges with less regulation)

The range you wrote down is one that most governments have agreed to be used for FM radio broadcasts. There is another range allocated for AM radio.

Other uses are for TV broadcasts, Airport communications, Mobile phone communications etc etc. An FM radio manufacturers won’t bother to detect transmissions at these frequencies outside the allocated ranges since it will not have any radio broadcasts.