The Theory and Application of the Radiation Mutual-Coupling Factor

The network equations for determining mutual impedance between a pair of radiating elements are analyzed and a new equation is determined in which the mutual impedance is expressed in terms of the self-impedances of the radiating elements and a new parameter designated as the radiation mutual-coupling factor Mr. A technique is outlined whereby this new parameter can be isolated and accurately measured despite the presence of discontinuities at the base of the radiating element to which a slotted line is connected. The technique is demonstrated for the case of a pair of identical quarter-wave monopoles and the results compared with the theroetical values interpolated from King's approximate second-order solution. The technique is then applied to the case of a pair of identical axial mode helical radiators.