Iterative Solution to Resonant Near-field Coupling Adjustments between Different Electrically Small Antennas

In this paper, iterative procedures based on Banach fixed-point theorem of adjusting transmitter and receiver impedances for achieving the maximum near-field power transfer performances are explored. As the background of proposed methods for controlling frequency splitting, an important phenomenon that occurs when two antennas are coupled in near-field, the analysis of the resonant near-field coupling using spherical mode theory-antenna model is applied. Methods of recursive alternate system tuning, critical coupling, and conjugate matching are mutually compared, and selection among them is given on disposal to user to achieve aimed performances.