Derivation Of The Normalized Site Attenuation Mutual Coupling Correction Factor And An Improved Method Of Antenna Factor Determination

The mutual coupling correction factor is used in ANSI C63.4-1991 site attenuation procedures to correct the antenna factors of resonant dipoles at a distance of three meters and arrive at values of measured normalized site attenuation. The correction factor accounts for nonlinearities of attenuation versus distance for resonant dipoles in close proximity. A derivation of the correction factor is given here in which it is shown that the factor is composed of effects due to mutual impedance, changes in aperture, and changes in effective height. The insights gained from this derivation lead to improved methods of deterniining resonant dipole antenna factors through the elimination of two approximations which are used in the present ANSI C63.5-1988 procedures.