On Spatial Visualization of Mutual Coupling With Applications to Small Embedded Antennas

Mutual coupling between antennas is a key parameter in multi-antenna systems. The present paper describes a method to map contributions to the magnitude of the mutual coupling spatially on surfaces between the ports. The method utilizes the reaction theorem for electromagnetic fields to obtain the contribution of the coupling from different regions. The derived result is valid for and applied to the strong-coupling regime, where the mutual impedance is of the same order as the self-impedance.