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Consider a Yagi–Uda consisting of a reflector, driven element, and a single director as shown here. The driven element is typically a 1 ⁄ 2 λ dipole or folded dipole and is the only member of the structure that is directly excited (electrically connected to the feedline). All the other elements are considered parasitic. That is, they ...
A folded dipole is, technically, a folded full-wave loop antenna, where the loop has been bent at opposing ends and squashed into two parallel wires in a flat line. Although the broad bandwidth, high feedpoint impedance, and high efficiency are characteristics more similar to a full loop antenna, the folded dipole's radiation pattern is more ...
Yagi antenna with one driven element (A) called a folded dipole, and 5 parasitic elements: one reflector (B) and 4 directors (C). The feed line leading to the receiver is not shown; it attaches to the driven element at D. The antenna radiates radio waves in a beam toward the right.
The two-wire version is often described as a "squashed loop antenna", since the total length of wire is one wavelength, and efficiency / radiation resistance of the folded dipole is very high: 4× that of a single dipole, [citation needed] analogous to the high efficiency of large loops. Any number of similar parallel wires may be added, with ...
Moore describes his antenna as "a pulled-open folded dipole". While the main point of Moore's patent was the two-turn single loop design, which is not the antenna termed "quad" today, the patent does include a mention and illustration of a two-element unidirectional "quad", and describes the time when the full wave loop concept was developed:
[70] [123] [71] If the ground plane is large enough, the radio waves from the remaining upper half of the dipole (a) reflected from the ground plane will seem to come from an image antenna (b) forming the missing half of the dipole, which adds to the direct radiation to form a dipole radiation pattern. So the pattern of a monopole over a ...
It consists of 175 folded dipole antennas. An early phased array , the antenna radiated a vertical fan-shaped beam which could be swept horizontally across the airspace in front of the antenna. 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 .
A "folded dipole" type of halo, similar to the original halo patent. [1] Gain along Y axis 1.2 dBi, gain along Z axis −10 dBi, gain along X axis −1.7 dBi. Fed at the center of the bottom conductor (at the red mark; feed-line not shown), supported at the center of the top conductor which is at ground potential for RF.