Numerically efficient techniques for computation of mutual coupling between co-planar circular apertures

Reflector antenna feeds often consist of an array of horn antennas whose apertures are co-planar, allowing the secondary radiation pattern to be controlled by the excitation of the array elements. The mutual coupling effects between the array elements can be described by a scattering matrix. By considering each mode in each horn aperture to be a port, the array can be treated as an N-port network. Potter horns, which radiate in the TE/sub 11/ and TM/sub 11/ modes, are sometimes used in horn arrays to minimize the primary pattern sidelobe level. This study considers the numerical computation of the scattering matrix of a co-planar array of circular aperture fed by Potter horns.