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The invention of the rectenna in the 1960s made long distance wireless power transmission feasible. The rectenna was invented in 1964 and patented in 1969 [2] by US electrical engineer William C. Brown, who demonstrated it with a model helicopter powered by microwaves transmitted from the ground, received by an attached rectenna. [3]
A passive electronically scanned array (PESA), also known as passive phased array, is an antenna in which the beam of radio waves can be electronically steered to point in different directions (that is, a phased array antenna), in which all the antenna elements are connected to a single transmitter (such as a magnetron, a klystron or a ...
The Eurofighter Typhoon combat aircraft with its nose fairing removed, revealing its Euroradar CAPTOR AESA radar antenna. An active electronically scanned array (AESA) is a type of phased-array antenna, which is a computer-controlled antenna array in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna. [1]
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 ...
Antennas are generally sensitive to signals only when they have a length that is a significant portion of the wavelength, or larger. Most antennas are at least 1 ⁄ 4 of the wavelength, more commonly 1 ⁄ 2 – the half-wave dipole is a very common design. For longwave use, this resulted in loop antennas tens of feet on a side, often with ...
The LH-16 was the first in the series of the Little L-Per line, and has now been discontinued, having been replaced by the LL-16 model. It uses a two-element yagi antenna, with a crystal oscillator-controlled double-conversion receiver, and may be attached to antennas for external use on aircraft or vehicles. On the face of the device there is
A Vivaldi antenna or Vivaldi aerial [1] or tapered slot antenna [2] is a co-planar broadband-antenna, which can be made from a solid piece of sheet metal, a printed circuit board, or from a dielectric plate metalized on one or both sides. Patterned Vivaldi antenna, made from double-sided printed circuit board material
For this reason, when attaching a twin-lead line to a coaxial cable connection, such as the 300 Ω twin-lead from a domestic television antenna to the television's 75 ohm coax antenna input, a balun with a 4:1 ratio is commonly used. Its purpose is double: First, it transforms twin-lead's 300 Ω impedance to match the 75 Ω coaxial cable ...