Analysis of mutual coupling in a cavity-backed coaxial array of annular-slot antennas

The problem of mutual coupling in a coaxial array of annular-slot antennas is formulated in terms of a magnetic-field integral equation (MFIE). The MFIE is solved numerically, under the assumption of narrow slot width, using a moment method with a Fourier basis and point matching. The operation of the array under multiport excitation is analysed, and an impedance matrix representation of the multiport antenna is calculated. Results predicted by the theory are shown to be in good agreement with experimental measurements on a two-port, two-element coaxial annular-slot array