Loop Antennas are loops of wires which are used as antennas. There are two types of loop antennas. Small loops and large loops. Small loop antennas have the primary gain in the axis of the loop while large loop antennas have the primary propagation/gain perpendicular to the loop. Large loop antennas are effectively dipole antennas where the tops of the dipoles are connected.

Loop antennas are typically used for UHF TV antennas. The UHF TV antennas can be used for High Defignition (HD) television. UHF loop antennas are large loops and thus have the primary gain perpendicular to the loop. Older bow tie antennas are also examples of UHF loop antennas. Wikipedia has more information on loop antennas, but the signal propagation information is currently incorrect.