A Non-contact Choke Structure for Broadside Adjustable Waveguide Phase Shifter

Broadside adjustable waveguide phase shifters (BAWPS) are widely used for phase adjustment of high-power microwaves (HPM) due to their simple structure and high power tolerance. However, due to the internal slot structure, it is inevitable to have electromagnetic compatibility (EMC) problems, which is a serious safety hazard in HPM applications. In this paper, a non-contact choke structure is designed by combining the structure and operation mechanism of BAWPS. By loading L-shaped choke slots on the metal isolation plate, it can satisfy the mechanical transmission and have good microwave suppression capability, which can effectively avoid electromagnetic crosstalk. In addition, the thickness of the isolation plate is effectively reduced by adding dielectric shims. Simulation results show that the BAWPS loaded with the designed non-contact choke structure is able to suppress the return loss below -20 dB and the insertion loss within 0.05 dB over the 360° phase shift. The energy leakage through the aperture is less than -90 dB, which has significant microwave protection effect.