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Frequency Range
Frequencies in the VHF band designation range from 50 to 330 megahertz. Megahertz is a measurement of cycles per second in a radio frequency signal; a measurement of one hertz is equal to one cycle per second. Very high frequency signals range from 50,000,000 cycles per second to 330,000,000 cycles per second. VHF frequencies are among the slowest of any usable band designation. Ultra-high frequency, or UHF, ranges from 300 MHz to 1 gigahertz. L-band frequencies range from 1 to 2 GHz, and other bands range up to 40 GHz frequencies.
History
VHF-band frequencies were the standard for many of the radio technologies in use during World War II. After WWII, VHF radar technology had a large presence in Russia, which gained access to the technology through confiscated German equipment. However, by the end of the Cold War, VHF frequencies began to be replaced by faster frequencies capable of quicker setup and responses that were more accurate.
Problems
The use of the VHF frequency range for radar purposes began to diminish after the Cold War due to newer radar technologies and the time consuming process of setting up a VHF radar system. Some military VHF radar systems could take up to two days to setup properly. Radar systems in the VHF band designation are also susceptible to interference from radio stations and television signals that use frequencies near the VHF range. Faster band designations are more accurate and better used for missile guiding, mapping and weather forecasting.
Uses
The typical usage for radar frequencies in the VHF band designation is for long-range surveillance. In military applications, VHF radar systems are generally used to track aircraft locations or detect other radar systems. VHF radar systems developed by Russia can detect airborne targets with a 27,000-meter altitude at a range of 330 kilometers. At a 500-meter altitude, these systems can detect aircraft at 50 kilometers.