International and national regulation of radio frequencies covers the frequency range between 9 kHz and 3,000 GHz. However, due to economic and technical reasons, the use of radio frequencies is currently restricted to up to 80 GHz. That corresponds to less than 3 % of the entire regulated radio spectrum.
Radio frequencies propagating with the speed of light is a natural resource that does not run down or decrease by use.
There are several things that contribute to the usability of radio frequencies. A radio transmitter affects all other radio equipment in its coverage area. The nearer the equipment is to each other both in terms of frequencies and geographically, the greater the effect. If the interaction is strong enough, it means
- harmful interference
- reduced transmission capacity or
- reduced transmission quality.
The radio frequency characteristics set restrictions for their exploitation. The manufacturing of radio equipment becomes more difficult and more expensive on higher frequencies.
The characteristics of propagating radio waves also make it more difficult to use higher frequencies for most purposes. In Finland, approximately 95 % of the radio equipment subject to licence use frequencies under the 10 GHz band and 99 % use frequencies under the 25 GHz band. When radio equipment exempted from licensing are taken into account, approximately over 99 % of all radio equipment work on frequencies below 10 GHz.