Compensation Theorems for the EM Coupling Between Two Multiport Antennas

The electromagnetic (EM) field transfer between two antenna systems is inevitably affected by the presence of neighboring objects located in the antenna's (radiative) coupling path. A convenient tool to describe the impact of such an object is found in EM compensation theorems. The concept of compensation is well known in standard electrical network theory where it furnishes an expedient methodology for calculating the effect of a change in the value of a circuit element. Compensation theorems in EM theory are frequently used in conjunction with the concept of surface impedance. This chapter applies reciprocity theorems of both the time‐convolution and time‐correlation types to introduce the EM compensation theorems describing the impact of a scattering object on the EM field transfer between two multiport antenna systems. In the reciprocity analysis, it describes the change in the corresponding transfer impedance matrices.