Modal analysis of cavity-backed and probe-fed rectangular patch arrays

A mode-matching method for the analysis of an infinite periodic array of cavity-backed and probe-fed rectangular patch radiators is presented. The radiator in the unit cell may be multi-layered and contain parasitic patches. Each section of the radiator is represented either by a dielectric-loaded waveguide or a waveguide with an inner conductor. The modes of the latter are obtained in closed form by a transverse resonance technique. The end free-space section is modelled as a Floquet waveguide. Each junction discontinuity is characterised by a generalised scattering matrix. The sections are then combined to give an overall S-matrix description of the radiator in an array environment. Predictions from the proposed method show good agreement with measured results