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Small antennas of any kind are inefficient, but when a full-sized antenna is not practical, making a small loop with a perimeter as close to 1 / 2 wave as possible (although usually no more than 0.3 wave) makes the small loop better for transmitting, although it sacrifices or outright loses the precise "null" direction of smaller small ...
Full-wave loops have the highest radiation resistance, and hence the highest efficiency of all antennas: Their radiation resistances are a few hundreds of Ohms, whereas dipoles and monopoles are tens of Ohms, and small loops and short whip antennas are a few Ohms, or even fractions of an Ohm.
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 ...
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:
Antenna arrays may employ any basic (omnidirectional or weakly directional) antenna type, such as dipole, loop or slot antennas. These elements are often identical. Log-periodic and frequency-independent antennas employ self-similarity in order to be operational over a wide range of bandwidths.
A full-wave loop antenna is slightly more than two half-wavelengths in circumference, which is a bit more than double the size of a halo antenna designed to operate on the same frequency. In contrast, the two semi-circles of a resonant loop, each is a half wavelength long.
Indoor antennas are designed to be located on top of or next to the television set, but are ideally placed near a window in a room and as high up as possible for the best reception. [1] The most common types of indoor antennas are the dipole [2] ("rabbit ears"), which work best for VHF channels, and loop antennas, which work best for UHF. [3]
The AT&T receiving Beverage antenna (left) and radio receiver (right) at Houlton, Maine, used for transatlantic telephone calls, from a 1920s magazine. The Beverage antenna or "wave antenna" is a long-wire receiving antenna mainly used in the low frequency and medium frequency radio bands, invented by Harold H. Beverage in 1921. [1]
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