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The second antenna is a reference antenna, which points rigidly at the first antenna. Each antenna is alternately connected to a transmitter having a particular source impedance, and a receiver having the same input impedance (the impedance may differ between the two antennas).
"King Andrew the First" is an American political cartoon created by an unknown artist around 1832. [1] The cartoon depicts Andrew Jackson , the 7th United States president , as a monarch , standing before a throne in a reminiscent of a playing-card king.
Forms of the reciprocity theorems are used in many electromagnetic applications, such as analyzing electrical networks and antenna systems. [1] For example, reciprocity implies that antennas work equally well as transmitters or receivers, and specifically that an antenna's radiation and receiving patterns are identical.
Examples of passive components deliberately designed to be non-reciprocal include circulators and isolators. [3] The transfer function of a reciprocal network has the property that it is symmetrical about the main diagonal if expressed in terms of a z-parameter, y-parameter, or s-parameter matrix. A non-symmetrical matrix implies a non ...
A high-gain antenna (HGA) is a directional antenna with a focused, narrow beam width, permitting more precise targeting of the radio signals. [1] Most commonly referred to during space missions , [ 2 ] these antennas are also in use all over Earth , most successfully in flat, open areas where there are no mountains to disrupt radiowaves.
Antenna directivity is the ratio of maximum radiation intensity (power per unit surface) radiated by the antenna in the maximum direction divided by the intensity radiated by a hypothetical isotropic antenna radiating the same total power as that antenna. For example, a hypothetical antenna which had a radiated pattern of a hemisphere (1/2 ...
English: Diagram of a J-pole antenna, a vertical end-fed half-wave omnidirectional transmitting antenna used in the shortwave frequency bands. It consists of a vertical element a half wavelength (/) long, fed in series with a quarter wavelength (/) transmission line stub, with the coaxial cable feedline (F) from the transmitter attached along the stub.
Animation of an omnidirectional half-wave dipole antenna transmitting radio waves. The antenna in the center is two vertical metal rods, with an alternating current applied at its center from a radio transmitter (not shown). Loops of electric field (black lines) leave the antenna and travel away at the speed of light; these are the radio waves ...