Broadening Misalignment Tolerance Using Broadside Coupled Wedge-Waveguide to Microstrip Inline Transition for MMIC Packaging

A broadside aperture coupling was utilized instead of end-wall aperture coupling for millimeter wave inline waveguide-to-microstrip transition (WMT), allowing a larger misalignment tolerance of ±250 um in the vertical direction and ±300 um in the horizontal direction within the insertion loss degradation of 0.1 dB. Additionally, a simple wedge waveguide configuration eliminated the necessity for complex taper or ridge waveguide sections. It simplifies manufacturing and testing procedures by eliminating the need for E-plane or H-plane splits. Furthermore, the transition exhibits broadband and low-loss performance. The fractional bandwidth reached as high as 44%, while the insertion loss of the back-to-back transition was measured at 8.5 dB, which includes the loss from the 1-meter-long waveguide (5.5 dB). The transition is well-suited for microwave and sub-millimeter frequencies due to its low loss, broad bandwidth, compact design, and ease of integration with MMICs.