Essential Characteristics of Thin-Wire Elliptical Loops

Elliptical loop antennas represent a natural generalization of circular loop antennas, which have themselves received substantial attention in the last decade. The characteristics of the latter were extended to the high gigahertz and low terahertz region, where lossy materials play a major role. This article seeks to extend these derivations to elliptical loops as well as demonstrate that elliptical loops, possessing more degrees of freedom than their circular counterparts, afford additional benefits. The asymmetric geometrical parameters of elliptical loops force some modifications to the standard calculational procedure, resulting in a closed-form solution to the fundamental equations and a computationally fast method of solution. Results show a high level of accuracy compared to full-wave solvers and reveal some remarkable features of the elliptical loops. At low frequencies, the admittance plots indicate higher Q values at the resonances for elliptical loops than those of circular loops. The higher Q values correspond to increasing ellipticity. At higher frequencies, loss occurs in metals, with resonance reaching saturation in the infrared as expected with circular loops. Interestingly, it is also shown that elliptical loops can be properly engineered to radiate near-pure multipoles of a given order, further distinguishing their performance from that of circular loops.