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Very high frequency (VHF) is the ITU designation [1] [2] [3] for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high ...
Many of these services require non-removable antennas or place restrictions on antenna size, height or gain. The high-VHF band (137–174 MHz) and UHF bands (325, 900 MHz) are the most popular aside from the 25–28 MHz "HF CB" bands.
Antennas which have these inductors built into their bases are called base-loaded whips. The rubber ducky is an electrically short quarter-wave antenna in which the inductor, instead of being in the base, is built into the antenna itself. The antenna is made of a narrow helix of wire like a spring, which functions as the needed inductor. The ...
A directive antenna with moderate gain of about 8 dBi often used at UHF frequencies. Consists of a dipole mounted in front of two reflective metal screens joined at an angle, usually 90°. Used as a rooftop UHF television antenna and for point-to-point data links. Parabolic The most widely used high gain antenna at microwave frequencies and above.
Their compact size makes helicals useful as antennas for mobile and portable communications equipment on the HF, VHF, and UHF bands. [citation needed] A common form of normal-mode helical antenna is the "rubber ducky antenna" used in portable radios. A handheld two-way radio, with the rubber sleeve removed from the antenna.
Land mobile radio systems use channels in the VHF or UHF bands, since the antennas used at these short wavelengths are small enough to mount on vehicles or handheld transceivers. Transmitter power is usually limited to a few watts, to provide a reliable working range on the order of 3 to 20 miles (4.8 to 32 km) depending on terrain.