Q-band waveguide-to-suspended-stripline transition with DC/IF

A waveguide-to-suspended-stripline transition with DC/IF return path is proposed in this work. The DC/IF return path is fulfilled by directly connecting the end of the probe to the metallic wall of the waveguide. The dimensions of the probe, the input match suspended-stripline, and the reduced height waveguides are optimized to achieve broadband performance. The measured results of a Q-band waveguide-to-suspended-stripline transition prototype show the insertion loss is less than 0.25 dB, and the return loss is higher than 15 dB with frequencies from 37 to 49.8 GHz. The essential substrate size of the Q-band transitions measures 3.8×2.84 mm². This compact waveguide-to-suspended-stripline transition is useful for millimeter-wave band integrated circuits designed with Schottky diodes to provide the DC/IF return path.