A Compact Millimeter-Wave Phase Shifter Integrated Variable Coupler in SIW Technology for Beam-forming Applications

This work presents an innovative, compact phase shifter integrated variable coupler in substrate-integrated waveguide (SIW) technology for millimeter-wave beam-forming applications. The phase-shifting mechanism leverages rectangular slots on the top and bottom walls of the SIW, enabling a precise and tunable phase shift of ±60◦. This phase shifter is functionally embedded into a cruciform directional coupler to realize variable coupling with arbitrary phase shift, combining functionality in a single, unified component. To validate this concept, seven prototypes are fabricated, each operating at a center frequency of 37 GHz, and offering variable coupling and phase-shift configurations (3 dB, 1 dB, 5 dB, ±60◦, and ±30◦). Characterization of these prototypes confirms the effectiveness and flexibility of the design, marking a significant advancement in compact, multi-functional millimeter-wave components. The proposed integrated design functions as a single component, ideal for advanced beam-forming networks, including Generalized Joined Coupler Matrix (GJC) architectures.