A rigorous and efficient full wave theory of multiport branch-guide couplers for contoured beam antennas is presented. Contoured beam antennas find wide use in modern satellite communication systems. The key element of these antennas is a beamforming network incorporating multiport branch-guide couplers to generate the necessary amplitude and phase distribution on the aperture feed.

The analysis of 2N-port branch-guide couplers is based on Galerkin's method taking into account the field edge condition and a generalized scattering matrix method. Numerical results are in a good agreement with the theoretical and experimental data of other works. Some optimized multiport branch-guide couplers are considered.