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A common design for a counterpoise is a series of radial wires suspended a few feet above the ground, extending from the base of the antenna in all directions in a "star" pattern, connected at the center. [2] The counterpoise functions as one plate of a large capacitor, with the conductive layers in the earth as the other plate. [2]
Often random wire antennas are also (inaccurately) referred to as long-wire antennas.There is no accepted minimum size, but actual long-wire antennas must be greater than at least a quarter-wavelength ( 1 / 4 λ) or perhaps greater than a half ( 1 / 2 λ) at the frequency the long wire antenna is used for, and even a half-wave may only be considered "long-ish" rather than "truly ...
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]
The attachment points at the tops are interconnected by a wire one half-wavelength long, which serves as both a counterpoise wire and a crossover phasing feedline. The verticals are the radiators and function as a minimal two-element curtain array, similar to a bobtail curtain.
The antenna wire, right, has a clip to attach to metal objects such as a bedspring, which serve as an additional antenna to improve reception. A crystal radio receiver , also called a crystal set , is a simple radio receiver , popular in the early days of radio.
The vertical wire that carries current from the feedpoint at the base to the top; unbalanced current in the vertical segment generates the emitted radio waves. Ground system Either wires buried in the ground under the antenna or sometimes wires suspended a few feet above ground (a counterpoise) acts like the other plate of the capacitor.
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In a few cases where rocky or sandy soil has too high a resistance for a buried ground, a counterpoise is used. [11] This is a radial network of wires similar to that in a buried ground system, but lying on the surface or suspended a few feet above the ground.