Calculation of antenna mutual coupling from far radiated fields

Mutual coupling between a pair of identical array elements is calculated from far field radiation. The reaction theorem is used on a single element to carry out a mutual coupling calculation. Evaluation of the reaction integral over a spherical surface surrounding a single waveguide element produces results better than the conventional aperture surface integral when using far fields. The method provides a simple tool for the estimate of mutual coupling given knowledge of the far field radiation of a single element. This is of great advantage during the development of array elements of unusual geometry, where analysis or other measurement techniques are difficult or less convenient.