Wideband probe-type waveguide-to-microstrip transition for V-band applications

A novel broadband probe-type waveguide-to-microstrip transition adapted for operation in V band is presented. The transition is realized on a standard high frequency printed circuit board (PCB) fixed between a standard WR-15 waveguide and a simple backshort. The microstrip-fed probe is placed at the same side of the PCB with the backshort and acts as an impedance matching element. The proposed transition additionally includes two through holes implemented on the PCB in the center of the transition area. Thus, significant part of the lossy PCB dielectric is removed from that area providing wideband and low-loss performance of the transition. Measurements show that the designed transition has the bandwidth of 50-70 GHz for the -10 dB level of the reflection coefficient with the loss level of only 0.75 dB within the transition bandwidth.