RF & Wireless


VHF and UHF broadcasting facilities remain based around terrestrial transmitters for DVB-T (for TV) and also for DAB-T (Digital Audio Broadcast Terrestrial, for radio)

UHF is the most commonly used frequency bands for transmission of television signals. Modern mobile phones also transmit and receive within the UHF spectrum. UHF is widely used by public service agencies for two-way radio communication, usually using narrowband frequency modulation, but digital services are on the rise. Narrowband radio modems use UHF and VHF frequencies for long range data communications e.g. for supervision and control of power distribution networks and other SCADA and automation applications. There has traditionally been very little radio broadcasting in this band until recently. The Global Positioning System also uses UHF. VHF propagation characteristics are ideal for short-distance terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter (see formula below). Unlike high frequencies (HF), the ionosphere does not usually reflect VHF radio and thus transmissions are restricted to the local area (and don't interfere with transmissions thousands of kilometers away). VHF is also less affected by atmospheric noise and interference from electrical equipment than lower frequencies. Whilst it is more easily blocked by land features than HF and lower frequencies, it is less affected by buildings and other less substantial objects than UHF frequencies.