Input impedance modeling of patch and semi-rectangular substrate integrated waveguide cavity hybrid antenna

A complete equivalent-circuit model of input impedance is developed for a hybrid antenna, which consists of a Half Mode Substrate Integrated Waveguide (HMSIW) resonator and a microstrip patch. An accurate circuit model is derived using Transmission Line (TL) model and lumped-element. The results based on the circuit modeling are presented and compared with those obtained using full-wave simulation. The proposed model, for the first time, clarifies fundamental characteristics of the input impedance of the hybrid antenna, which are verified by the results of a full-wave simulation and those obtained by measurement.