What Is the Difference Between VHF & UHF Radios?
VHF (very high frequency) and UHF (ultra-high frequency) are classes of radio waves on the electromagnetic spectrum. Both frequencies have a wide variety of applications, such as transmission of broadcast television and radio signals. Appliances such as cordless phones and walkie-talkies use UHF radio signals for wireless communication.
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Radio Waves
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A radio transmission is radiation that comprises electric and magnetic fields that are arranged in a perpendicular alignment to each other. Both fields contain energy that travels back and forth between them. Each radio wave is measured by its frequency, or cycle per second in units of "hertz." The higher the radio wave's frequency, the more energetic it is. This determines a radio wave's behavior and movement as it propagates out from its point of origin.
VHF Radio Waves
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VHF radio waves are also known as "Frequency Modulated" or the FM band. Its frequency range is between 88 and 108 MegaHertz (MHz). This range of frequencies can carry large amounts of information with a larger dynamic range, hence their use in television broadcasts. The disadvantage to FM signals is that they require a line of sight between the source of transmission and the placement of a receiver. Obstacles between the two points, such as hills and buildings, can degrade the FM transmissions.
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UHF Radio Waves
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UHF radio waves lie in the frequency range of 300 MHz and 3,000 MHz (also referred to as microwave frequencies). UHF waves are used for television broadcast as well as mobile phones, wireless networking, GPS and satellite radio. Government and first-responders (police, fire, ambulance) also use the UHF band for communications.
Commercial Radio
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VHF signals on the FM radio band has wide variety of commercial stations that use its frequencies. Because of the wider dynamic range that its signals can carry, the sound quality of FM radio is high. VHF radio can transmit both analog and digital signals. Satellite radio (also known as XM and Sirius) transmits UHF signals broadcast from satellites. Because UHF signals have small wavelengths, receiving antennas can be compact, and installed in vehicles (the primary market for commercial satellite radio).
Comparisons
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UHF radio waves have a higher data rate (and therefore contain more information) than a VHF radio wave. UHF signals are also able to better penetrate obstacles such as clouds and buildings, whereas VHF waves can be blocked by them. VHF radio waves can propagate without significant signal loss from 25 to 50 miles. By comparison UHF radio waves can propagate for longer distances (up to 100 miles) without loss or distortion. UHF signals require less power for transmission as compared to VHF signals.
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- Photo Credit radio telephone tower. image by mdb from Fotolia.com
