Magnetic Loop Antennas
What are magnetic antennas?
‘Magnetic' because they pick up the magnetic component of an electromagnetic field, unlike the usual antenna forms (dipoles, yagi antennas, vertical antennas), which only respond to the electrical component.
Magnetic antennas can be built very compact, good for limited spaces or 'mobile' use, e.g. on boats with limited space. Radials or other counterweights are not necessary, the radiation is largely independent of the distance of the antenna to the ground.
At the resonance frequency, magnetic antennas are quite narrow-banded. This has the advantage that on the one hand only few harmonics are radiated, on the other hand the antenna acts as a very narrow-band additional preselector and thus prevents overdriving of the usually quite broadband receivers by signals far away from the receiving frequency.