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Random wire antenna. A wire antenna kit, with a coil of wire, strain insulators and a balun. When installed the wire is supported by buildings or trees using the insulators to prevent a short circuit to ground. A random wire antenna is a radio antenna consisting of a long wire suspended above the ground, whose length does not bear a particular ...
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.
Massive. v. t. e. In electrical engineering, electrical length is a dimensionless parameter equal to the physical length of an electrical conductor such as a cable or wire, divided by the wavelength of alternating current at a given frequency traveling through the conductor. [ 1 ][ 2 ][ 3 ] In other words, it is the length of the conductor ...
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.
A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. [1][2][3] The driving signal from the transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the lower end of the ...
When the antenna is fed at some other point, the formula requires a correction factor discussed below. In a receiving antenna the radiation resistance represents the source resistance of the antenna, and the portion of the received radio power consumed by the radiation resistance represents radio waves re-radiated (scattered) by the antenna. [8 ...
T2FD antenna. A 20-meter-long T²FD antenna, covering the 5-30 MHz band. The Tilted Terminated Folded D ipole (T²FD, T2FD, or TTFD) or Balanced Termination, Folded Dipole (BTFD) - also known as W3HH antenna - is a general-purpose shortwave antenna developed in the late 1940s by the United States Navy. [1][2] It performs reasonably well over a ...
2.4 GHz helical antenna radiation pattern (NEC simulation) The Numerical Electromagnetics Code, or NEC, is a popular antenna modeling computer program for wire and surface antennas. It was originally written in FORTRAN during the 1970s by Gerald Burke and Andrew Poggio of the Lawrence Livermore National Laboratory.