Novel In-Line Microstrip-to-Waveguide Transition Based on E-Plane Probe T-Junction Structure

In this letter, a novel in-line E-plane probe microstrip-to-waveguide (M2W) transition is proposed. The proposed in-line transition structure consists of a waveguide T-junction which has two short-circuited branch waveguides with a quarter-wavelength difference in length and a microstrip line fed probe that is in line with the main waveguide. A W-band in-line M2W transition is designed based on the proposed structure. Back-to-back measured results show that the reflection coefficient is better than -10 dB and the insertion loss is less than 1 dB over the full W-band. The measurements agree well with the simulations.