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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]
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.
In transmitting antennas the impedance of the antenna must be matched to the feedline for maximum power transfer. A half wave whip antenna (length of ) has somewhat higher gain than a quarter wave whip, but it has a current node at its feedpoint at the base of the rod so it has very high input impedance. If it was infinitely thin the antenna ...
A common shape today is the batwing or superturnstile antenna, used for television broadcasting in the VHF or UHF bands [8] The batwing shape of each element produces an antenna with wide impedance bandwidth. [1] Up to eight batwing antennas are usually stacked vertically and fed in phase to make a high gain omnidirectional antenna for TV ...
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.