3D Printed Waveguide Phase Shifter for Butler Matrix Network

This paper presents a 45° phase shifter based on waveguide technology at 28 GHz. The phase shifter is one of important components in Butler matrix network which controls the phases towards the output ports. The proposed phase shifter is designed using rectangular waveguide cavity resonator technique. The quality factor with tuned iris coupling between ports and resonator is used to achieve the desired 45° phase shift. In this work, phase shifter is implemented with one cavity resonators and two symmetric irises coupling. The design is simulated using CST software and 3D metal printed using selective laser melting technique. The measured reflection of less than -10 dB and a 42.5° phase shift are obtained.