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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. Multiwire broadcast T-antenna of early AM station WBZ, in Springfield, MA, 1925.
In most antennas, the radiation from the different parts of the antenna interferes at some angles; the radiation pattern of the antenna can be considered an interference pattern. This results in minimum or zero radiation at certain angles where the radio waves from the different parts arrive out of phase , and local maxima of radiation at other ...
English: Diagram of T antennas (flat-top antennas), a simple type of long wire radio antenna used at low frequency (LF), medium frequency (MF), and shortwave frequencies. . The red parts are insulators, the grey are supporting tow
English: Common types of T antenna, a wire radiio antenna used at low and medium frequencies. The antenna consists of a vertical wire which serves as a monopole radiating element fed at the bottom, attached to one or more horizontal wires which serve as a capacitive topload to increase the current in the vertical wire.
German physicist Heinrich Hertz first demonstrated the existence of radio waves in 1887 using what we now know as a dipole antenna (with capacitative end-loading). On the other hand, Guglielmo Marconi empirically found that he could just ground the transmitter (or one side of a transmission line, if used) dispensing with one half of the antenna, thus realizing the vertical or monopole antenna.
The typical height of a 'T' antenna is shorter than the quarter wavelength required for resonance. A 'T' antenna is distinguished from the similar 'L' antenna by the place where the dangling, radiating wire attaches to the horizontal cross wire: For the 'T' antenna the dangling wire attaches to the exact center of the top horizontal wire.
English: Diagram of a quarter-wave monopole antenna and its image (dotted line) reflected by a ground plane. Label in english. When a monopole antenna is mounted above a ground plane such as the Earth, the radio waves emitted downwards by the antenna reflect off the ground plane.
An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. [ 1 ] : p.149 [ 2 ] The individual antennas (called elements ) are usually connected to a single receiver or transmitter by feedlines that feed the power to the elements in a specific phase ...