A CAD‐oriented approach for aperture‐coupled patch antennas

A simplified model is suggested for describing aperture-coupled patch antennas in CAD applications. The scattering parameters of the antenna are calculated by assuming a single mode distribution for the currents on the slot and on the microstrip-line. The coupling between the slot and the patch is represented by superimposing a contribution from a fundamental mode and that from higher order modes. The former is described by a complex eigenvalue of a cavity model with impedance walls. The latter is described by a parallel plate waveguide model, which properly accounts for the storage of reactive energy close to the slot. Numerical results are presented and compared with experiments. In particular, S-band patches have been fabricated and tested to demonstrate the accuracy of the model.