VHF, or very high frequencies, is the band of radio frequencies found between 30 MHz to 300 MHz. These frequencies exhibit excellent characteristics for short distance radio waves, and can provide clear signal transmissions, making them ideal for wireless microphone systems. One of the most common issues with the VHF band, however, is crowding: there are harsh limitations for available frequencies within this band, as the U.S. has traditionally broadcast television signals as well as powerful commercial signals on VHF.
UHF, or ultra high frequencies, lies within the radio band of 300 MHz and 3 GHz. Many communications devices use these frequencies, but many more available channels are open for short range use, making them ideal for wireless system operation. As these frequencies exist above the range of VHF, slightly more interference can be expected, as well as slightly smaller range, or the maximum distance from the unit's microphone transmitter to its receiver.
VHF systems require readily available components, keeping the prices of VHF units lower than UHF. Unit size is also effected, as UHF frequencies feature shorter wavelengths than VHF. Both units require the use of antennas to receive the signal. These antennas must be built in accordance with their operating frequency's wavelength, making UHF systems and antennas smaller and lighter than most VHF systems.
The VHF radio band can be crowded in many cities, with many communications devices attempting to share the same limited bandwidth. VHF systems, therefore, have been limited in transmission bandwidth to allow more units to operate at the same time. The UHF range allows more transmission bandwidth, increasing the dynamic range and overall sound quality of these wireless units, as well as more channels, allowing more units to operate simultaneously.