Tunable Substrate Integrated Waveguide Phase Shifter Using High Dielectric Constant Slab

This letter presents a low-cost, low-profile, and high-performance Ka-band continuously tunable substrate integrated waveguide (SIW) phase shifter. The proposed phase shifter consists of a slot cut on the SIW's broad wall and a high dielectric constant slab over the slot. The phase-shifting mechanism is based on perturbing the electric field of the SIW's fundamental mode, TE10-like, by putting a high dielectric constant slab over the slot of SIW structure to create slow wave phenomena. A prototype is designed, fabricated, and measured. The fabricated phase shifter exhibits linear phase-frequency response behavior with an average insertion loss less than 1.5 dB with an insertion loss variation less than 0.5 dB over a phase shift range of 275° in the operating frequency band (29-31 GHz). The phase shifter consumes a maximum of 25-mW power.