Horn Antenna
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| Horn Antenna |
A horn antenna or microwave horn is an antenna that consist of a flaring metal wave-guide shaped like a horn to direct radio waves in a beam. Horns are widely used as antenna at UHF and microwave frequency, above 300 MHz. they are used as feeders (called feed horns ) for larger antenna structures such as parabolic antenna , as standard calibration antenna to measure the gain of other antenna , and as directive antenna for such devices as radar guns, automatic door openers, and microwave radiometers. Their advantage are moderate directivity, low standing wave ratio (SWR), broad bandwidth, and simple construction and adjustment. in order to function properly, a horn antenna must be certain minimum size relative to the wavelength of the incoming or outgoing electromagnetic field. if the horn is too small or the wavelength is too large ( the Frequency is too low ), the antenna will not work efficiently.
Hone antenna are commonly used as the active element in a dish antenna. The horn is pointed toward the center of the dish reflector. the used of a horn , rather then a dipole antenna or any other type of antenna , at the dish reflector. It the focal point of the dish minimizes loss of energy (leakage ) around the edges of the dish reflector. It also minimizes the response of the antenna to unwanted signals not in the favored direction of the dish.
Parabolic Antenna
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