A New Transition from Microstrip Line to Rectangular Waveguide

A simple transition from microstrip to rectangular waveguide using an aperture coupled patch antenna radiating into the waveguide is proposed. In addition, two slightly modified versions are discussed, having some advantages with regard to ease of fabrication and therefore being more suitable for use in the mm-wave range. S-parameters of all three versions are calculated and measured. The analysis is based on a modified procedure of the well known spectral domain method. The remarkable advantage of this new transition compared to recent approaches is the fact that waveguide structures are necessary only on the back side of the planar circuit.