A broadband low-loss WR10 waveguide to microstrip line transition with T-shaped probe

A novel W-band WR10 waveguide to microstrip line transition is designed, simulated in a 3D full-wave EM simulation software, fabricated, and evaluated by measurements. The main advantages of this transition are frequency-flat transmission, low reflection, and uncomplicated fabrication. Simulation shows a reflection coefficient of better than -23 dB from 75 to 90 GHz for one hollow waveguide to microstrip line transition. The port reflections increase for a fabricted prototype with two transitions and a connecting microstrip line to a level of about −14 dB. This is mainly caused by fabrication tolerances. The overall transmission of the dual transition prototype is found at a very satisfactory level of about -4.8 dB at 90GHz for a connecting microstrip line with a length of 45mm corresponding to an estimated loss of approximately 0.6 dB for a single transition.