A Full $Ku$ -Band Reduced-Height Waveguide-to-Microstrip Transition With a Short Transition Length

A systematic design of a full Ku -band reduced-height waveguide-to-microstrip transition using commercial High Frequency Structure Simulator software is presented. The basic transition is composed of a shorted microstrip probe to a 50- Ω ridge waveguide. An impedance transformer necessary to adapt the 50-Ω ridge waveguide to a reduced-height waveguide was designed using multistage short-length ridge waveguides connected in cascade. The resulting transition length is 6.2 mm. The separately designed shorted microstrip probe transition and impedance transformer were combined and adjusted for full-Ku-band operation. The combined transition was fabricated and measured. The measured insertion and return losses are about 0.41 dB and below 15 dB for the full-Ku-band, respectively.