Single-sleeve waveguide-to-microstrip transition probe for full waveguide bandwidth

A simple E-plane waveguide-to-microstrip transition probe on quartz substrate is designed. Instead of using cascaded microstrip sections as impedance transformer, the transition probe adopting the structure analogous to monopole antenna with sleeve features a compact structure and tunable bandwidth. The sleeve contributes an additional resonant mode to transition probe, and the design is capable to cover whole waveguide band. The measured results show that this designed transition probe has the return loss less than -10 dB and insertion loss better than 0.36 dB in Q-band.