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The monopole antenna was invented in 1895 by radio pioneer Guglielmo Marconi; for this reason it is sometimes called the Marconi antenna. [4] [5] [6] The load impedance of the quarter-wave monopole is half that of the dipole antenna or 37.5 ohms. Common types of monopole antenna are
It is the most efficient antenna design found so far for this frequency range, achieving efficiencies of 70-80% where other VLF antenna designs have efficiency of 15-30% due to the low radiation resistance of the very electrically short monopole. [8] The antenna was invented by Boynton Hagaman of Development Engineering Co. (DECO) and first ...
A whip antenna is an antenna consisting of a straight flexible wire or rod. The bottom end of the whip is connected to the radio receiver or transmitter. A whip antenna is a form of monopole antenna. The antenna is designed to be flexible so that it does not break easily, and the name is derived from the whip-like motion that it exhibits when ...
English: Diagram of a ground plane antenna, a common omnidirectional monopole antenna used at VHF and UHF frequencies. It consists of a vertical whip antenna one quarter wavelength long, with 3 or 4 quarter wave rods extending from the base electrically connected to the ground side of the transmission line.
It is shaped like the Greek letter Π or an upside-down capital letter U, and is the loop antenna analog of a ground-mounted monopole antenna. Similar to how a vertical monopole uses its ground system to produce a "phantom" image of the rest of a dipole, the missing lower half of the half-loop is replaced by its ground-plane image. If shaped ...
The name comes from its resemblance to an inverted letter "L" (Γ). The T-antenna is an omnidirectional antenna, radiating equal radio power in all azimuthal directions, while the inverted-L is a weakly directional antenna, with maximum radio power radiated in the direction of the top load wire, off the end with the feeder attached.
A 1 / 4 λ monopole antenna and its ground image together form a 1 / 2 λ dipole that radiates only in the upper half of space. The vertical, Marconi, or monopole antenna is a single-element antenna usually fed at the bottom (with the shield side of its unbalanced transmission line connected to ground). It behaves essentially ...
An ideal monopole antenna radiates maximum power in horizontal directions at a height of 225 electrical degrees, about 5 / 8 or 0.625 of a wavelength (this is an approximation valid for a typical finite thickness mast; for an infinitely thin mast the maximum occurs at / = 0.637 [6]) As shown in the diagram, at heights below a half ...