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the upper half of a vertical full-wavelength loop antenna mounted on the ground (not to be confused with the visually similar but electrically different half-square antenna described below, under array antennas, [u] nor to be confused with the halo antenna, described next). The full loop is cut at two opposite points along its perimeter, and ...
The length of a whip antenna is determined by the wavelength of the radio waves it is used with. Their length varies from compact electrically short antennas 1 / 10 wavelength long, up to 5 / 8 wavelength to improve directivity. The most common type is the quarter-wave whip, which is approximately 1 / 4 wavelength long.
The AT&T receiving Beverage antenna (left) and radio receiver (right) at Houlton, Maine, used for transatlantic telephone calls, from a 1920s magazine. The Beverage antenna or "wave antenna" is a long-wire receiving antenna mainly used in the low frequency and medium frequency radio bands, invented by Harold H. Beverage in 1921. [1]
Small antennas of any kind are inefficient, but when a full-sized antenna is not practical, making a small loop with a perimeter as close to 1 / 2 wave as possible (although usually no more than 0.3 wave) makes the small loop better for transmitting, although it sacrifices or outright loses the precise "null" direction of smaller small ...
Not being close to 3 / 2 wave, this antenna's impedance has a large (negative) reactance and can only be used with an inductive impedance matching network (a tapped loading coil or a so-called antenna tuner). It is a desirable length because such an antenna has the highest gain for any dipole which isn't a great deal longer.
Due to their omnidirectional radiation pattern, vertical monopole antennas are commonly used in terrestrial radio communication systems in which the direction to the transmitter or receiver is unknown or constantly changing, [7] such as broadcasting, mobile two-way radios, and wireless devices like cellphones and Wi-Fi networks, [8] [4] because they radiate equal radio power in all horizontal ...
The radiation patterns of a vertical half-wave dipole, an omnidirectional antenna. The horizontal and vertical polar patterns are projections of the 3 dimensional pattern onto horizontal and vertical planes, respectively. An omnidirectional antenna radiates equal signal strength in all horizontal directions, so its horizontal pattern is just a ...
The vertical plane is used to plot an antenna's relative field strength perpendicular to the ground (which directly affects a station's coverage area) on a polar graph. Normally, the maximum of 1.000 or 0 dB is at the side (unless there is beam tilt), which is labeled 0°, to 90° at the top and −90° at the bottom.
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