Power transfer efficiency formulation for reciprocal and non-reciprocal linear passive two-port systems

Abstract

This paper formulates the power transfer efficiency of linear passive two-port systems. Focusing on the port voltages and currents, we express the efficiency in terms of impedance matrix components. Algebraic manipulation derives an explicit formula that opens up the vista on how the efficiency behaves on the complex load impedance plane. As a result, we reach a rigorous formula of the maximum efficiency without resorting to reciprocity assumption. This study originates in wireless power transfer engineering, but the hereby deduced formulas are even applicable to performance evaluation of non-reciprocal circuit networks such as ferrite isolators.