Analytical Formulation for Loop Antennas Valid from the RF to Optical Regime: A Review

Loop antennas are among one of the simplest antennas to construct. Yet, despite this fact, the mathematical complexity of the associated radiation integrals has complicated the understanding and modelling of such structures. Recently, a full analytical theory for the radiation properties of loop antennas has been derived, which is able to bridge this gap and provide a basis for better understanding the behavior of these antennas across all frequency ranges. Further, these models have been extended to include the effects of loading and coupling, as well as have revealed interesting properties such as superdirectivity by enabling rapid parametric studies and optimizations to be carried out.