Optimized Flange Designs for a Multigap-Waveguide Liquid Crystal Phase Shifter at Ka-Band

This paper extends the investigation of the MultiGap-WaveGuide (MGWG) liquid crystal (LC) phase shifter by analyzing the impact of different flange designs. The flange is identified as a key limiting factor affecting insertion loss and resonance behavior. To address this, a chamfered impedance transformer and a 2D photonic crystal (PhC) flange are designed, manufactured, and experimentally evaluated. The chamfered design eliminates unwanted resonances. The measured insertion loss for the circular and chamfered flanges ranges from 2.1 dB to 3.1 dB over 24 GHz to 38.5 GHz, with a maximum Figure of Merit (FoM) of 105°/dB at 30 GHz. Additionally, a phase tuning curve is presented, illustrating the continuous tunability of the phase shifter.