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The dipole is the simplest type of antenna from a theoretical point of view. [1] Most commonly it consists of two conductors of equal length oriented end-to-end with the feedline connected between them. [8][9] Dipoles are frequently used as resonant antennas.
A log-periodic antenna (LP), also known as a log-periodic array or log-periodic aerial, is a multi-element, directional antenna designed to operate over a wide band of frequencies. It was invented by John Dunlavy in 1952. The most common form of log-periodic antenna is the log-periodic dipole array or LPDA, The LPDA consists of a number of half ...
[1] [4] The far-field pattern of an antenna may be determined experimentally at an antenna range, or alternatively, the near-field pattern may be found using a near-field scanner, and the radiation pattern deduced from it by computation. [1] The far-field radiation pattern can also be calculated from the antenna shape by computer programs such ...
The monopole is often used as a resonant antenna. The rod functions as an open resonator for radio waves and oscillates with standing waves of voltage and current along its length. The length of the antenna, therefore, is determined based on the wavelength of the desired radio waves. The most common form is the quarter-wave monopole, in which ...
Near field: This dipole pattern shows a magnetic field B in red. The potential energy momentarily stored in this magnetic field is indicative of the reactive near field. Far field: The radiation pattern can extend into the far field, where the reactive stored energy has no significant presence.
The driven element is often a dipole. The parasitic elements act as resonators and couple electromagnetically with the driven element, and serve to modify the radiation pattern of the antenna, directing the radio waves in one direction, increasing the gain of the antenna. An antenna may have more than one driven element, although the most ...
Dipole. The magnetic field of a sphere with a north magnetic pole at the top and a south magnetic pole at the bottom. By comparison, Earth has a south magnetic pole near its north geographic pole and a north magnetic pole near its South Pole. In physics, a dipole (from Ancient Greek δίς (dís) 'twice' and πόλος (pólos) 'axis') [1][2][3 ...
A turnstile antenna, or crossed-dipole antenna, [1] is a radio antenna consisting of a set of two identical dipole antennas mounted at right angles to each other and fed in phase quadrature; the two currents applied to the dipoles are 90° out of phase. [2][3] The name reflects the notion the antenna looks like a turnstile when mounted ...