Rigorous analysis of large finite waveguide-fed slot arrays including the mutual internal and external higher-order mode coupling

Large finite waveguide-fed slot arrays are rigorously analyzed based on the combination of the external and internal full-wave scattering matrices which are computed using a Green's function approach and the mode matching technique, respectively. For calculating the external mutual fundamental and higher order mode coupling, the waveguide eigenvectors are expanded into subdomain functions. Slots of arbitrary cross-section are involved by computing the corresponding eigenvectors by a 2D finite element (FE) method. The mode matching technique yields the generalized scattering matrices (GSM) of the complete waveguide feed network. The method is verified by available measurements at 9.75 GHz for an array with 48 round-ended slots fed by transverse slots in a waveguide manifold.