The Effects of Varying the Location of Antenna Feed Gaps on Mutual Coupling Between Orthogonal Circular Loops

This work aims to investigate how varying the location of antenna feed gaps affect the mutual coupling between orthogonal circular loops. Since the orthogonal circular loops, which is a type of loop antenna array, provide better gain than a single loop antenna, investigating the mutual coupling on the array could contribute to the improvement of its radiation. Using the Method of Moment (MoM)-based simulation tool that computes the Z-parameters, which are the mutual impedances and self-impedances, this paper provides clearer three-dimensional illustrations and advances intuitive insights that would facilitate better understanding of the mutual coupling phenomenon. Prior studies mostly presented two-dimensional illustrations derived from analytical solutions on mutual coupling. The elements of the Z-matrix, namely mutual impedances, $\mathrm{Z}_{12}$ and $\mathrm{Z}_{21}$, and the self-impedances, $\mathrm{Z}_{11}$ and $\mathrm{Z}_{22}$, are clearly plotted against the rotational angles and carefully analyzed in order to effectively discuss the effects on mutual coupling when the relative locations of the feed gaps along the circular loops are varied.