Design of 60-GHz SIW short-slot couplers

The 0-dB and 3-dB 60-GHz SIW short-slot couplers designed based on a systematic approach are fabricated by a standard single-layer print circuit board process, which is more economical for mass-production than the advanced processes such as low temperature co-fired ceramic and thick-film process, etc. The systematic approach involves design equations, simulations and measurements. Starting with a set of explicit design equations for the short-slot couplers, one calculates the structure dimensions. The calculated dimensions are then optimized with full-wave simulation to finalize the design. With the use of noncoaxial multiport measurement technique, the characteristics of the components are acquired through a probe station and a two-port vector network analyzer. Measurement technique plays a critical role in the systematic design approach. By measuring at the intrinsic ports or the wave ports defined in the full-wave simulations, the couplers are ambiguously verified. The measured four-port S-matrices not only verify the SIW couplers, but also can be directly used in the follow-on design of the circuits with the integration of SIW couplers.