A WR-6 rectangular waveguide to microstrip transition and patch antenna at 140 GHz using low-cost solutions

A new WR6 rectangular waveguide to microstrip transition is developed based on the concept of slot coupling. The transition is designed having in mind the great limitations that exist in these high frequency ranges. A low-cost implementation is also pursued, avoiding complicated multilayer and assembly structures. As an example of application, a microstrip patch antenna is also designed at the WR6 center frequency, 140 GHz. The interconnection system here developed can help in measurement procedures of further microstrip radiating structures or can act as feed line for planar antennas. The transition is designed by means of 3D finite element electromagnetic simulators and built using common photolitography processes with commercial components. Measurements show a bandwidth of nearly 7 GHz for a return loss below -10 dB and low insertion loss around -0.7 dB within the transition bandwidth.