loop antenna
Loop antennas are loop antennas that respond to the horizontally polarized magnetic component of the electromagnetic field. They are therefore also called magnetic loop antennas.
The antenna radiator itself is a coil consisting of one or a few turns and is extremely broadband. In combination with a capacitor, a loop antenna forms an oscillating circuit with an extremely narrowband frequency response. The radiation pattern and the receiving frequency range of the loop antenna is determined by the size of the coil diameter and should be much smaller than lambda quarters in terms of antenna circumference.
The sensitivity of the broadband loop antennas is relatively low, only the narrowband resonance-based loop antennas are relatively sensitive. The loop of the antenna radiator consists of a circularly bent wire or aluminum tube. The antenna footpoint is symmetrical, and the footpoint impedance is about 50 ohms, which ensures optimal matching to balanced RF cables.
Loop antennas are relatively insensitive to electrical interference signals, since such interference caused by motors or fluorescent tubes usually has only a small magnetic component. The application range of loop antennas is in the VHF and UHF range. Corresponding antennas were formerly also used as indoor antennas because of their compactness.