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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 gain and input impedance of the antenna is dependent on the length of the whip element, compared to a wavelength, but also on the size and shape of the ground plane used (if any). A quarter wave vertical antenna working against a perfectly conducting, infinite ground will have a gain of 5.19 dBi and a radiation resistance of about 36.8 ohms.
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
The quarter-wave monopole, the most compact resonant antenna, may be the most widely used antenna in the world. The five-eighth wave monopole – length 0.625 λ, or 5 / 8 of a wavelength – is also popular, since at that length monopoles direct the greatest proportion of their radiated power horizontally, hence the best use of ...
Effective monopole radiated power (EMRP) may be used in Europe, particularly in relation to medium wave broadcasting antennas. This is the same as ERP, except that a short vertical antenna (i.e. a short monopole) is used as the reference antenna instead of a half-wave dipole. [7]
Typical feeder loops are 1 / 8 to 1 / 5 the size of the antenna's main loop, which gives transform ratios of 64:1 to 25:1, respectively. Adjusting the proximity and angle of the feeder loop to the main loop, and distorting the feeder's shape, both make small-to-moderate changes to the transform ratio, and allows for fine ...
Traveling wave antennas Traveling wave antennas are notably one of the few types of antennas that are normally not self resonant: Electrical waves induced by received radio waves travel through the antenna wire in the direction that the arriving RF signals are travelling. Only electrical waves traveling toward the feedpoint are collected; waves ...
Moore describes his antenna as "a pulled-open folded dipole". While the main point of Moore's patent was the two-turn single loop design, which is not the antenna termed "quad" today, the patent does include a mention and illustration of a two-element unidirectional "quad", and describes the time when the full wave loop concept was developed: