Iterative Solution to Resonant Near-Field Coupling Adjustments Between Different Electrically Small Antennas

In this communication, 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 the near-field, the analysis of the resonant near-field coupling using a spherical mode theory-antenna model (SMT-AM) 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 the user to achieve aimed performances.