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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 ...
The rubber ducky antenna is a form of normal-mode helical antenna. Electrically short antennas like the rubber ducky are used in portable handheld radio equipment at VHF and UHF frequencies in place of a quarter-wavelength whip antenna, which is inconveniently long and cumbersome at these frequencies. [2]
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.
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.
An example of a high-gain antenna is a parabolic dish such as a satellite television antenna. Low-gain antennas have shorter range, but the orientation of the antenna is relatively unimportant. An example of a low-gain antenna is the whip antenna found on portable radios and cordless phones. Antenna gain should not be confused with amplifier ...
If operating on VHF/UHF, this can mean a location on the top of a hill or cliff, with clear line of sight to the horizon. The main disadvantage is normally the power supply available. As normal mains grid power is unavailable, the /P operator may have to resort to batteries, portable generators, solar panels. [3] and wind turbines.