Parallel Plate Patch Antenna With Internal Rectangular Coupling Patches and TE$_{\rm N0}$ Mode Excitation

A parallel plate waveguide antenna is presented with microstrip patches as radiating elements. Rectangular patches are also placed inside the waveguide as coupling field structures from the waveguide to the radiating elements. The connections from the coupling to the radiating patches are made by means of vias. The field propagated along the parallel plate waveguide corresponds to a high order TE mode, creating virtual smaller rectangular waveguides in the parallel plate structure. An antenna prototype has been manufactured and measured. A 60% efficiency and 27 dBi antenna gain were obtained; with a 6.5% reflection bandwidth. Nevertheless, the resonant behavior becomes evident in the radiation pattern measurements.