Loop antenna
A loop antenna is a radio antenna consisting of a loop (or loops) of wire, tubing, or other electrical conductor with its ends connected to a balanced transmission line (or a balun).
Contents
Description
Within this physical description there are two very distinct antenna designs:
- The small loop (or magnetic loop) with a size much smaller than a wavelength
- The much larger resonant loop antenna with a circumference close to the intended wavelength of operation
Small loops
Small loops have a poor efficiency and are mainly used as receiving antennas at low frequencies. Except for car radios, almost every AM broadcast receiver sold has such an antenna built inside it or directly attached to it.
Small loop antennas are also used for radio direction finding.
Resonant loop antennas
Resonant loop antennas are relatively large, governed by the intended wavelength of operation.
Thus they are typically used at higher frequencies, especially VHF and UHF, where their size is manageable.
They can be viewed as a folded dipole deformed into a different shape, and have rather similar characteristics such as a high radiation efficiency.
Amateur radio
In amateur radio, loop antennas are often used for low profile operating where larger antennas would be inconvenient, unsightly, or banned.
Loop antennas are relatively easy to build.
See also
External links
- Loop antenna @ Wikipedia
