A Broadband Tunable Multilayer Substrate Integrated Waveguide Phase Shifter

A novel low loss, electronically controllable two-layer substrate integrated waveguide (SIW) phase shifter is presented in this letter. Wideband coupling between two layers ensures the wide bandwidth. PIN diodes are used to achieve electronic control of phase shifter. An equivalent circuit model for this device is developed and explained. A compact and low loss five-level digital phase shifter using the proposed structure is designed, fabricated and measured. The simulated results excellently agree with measured results. Including the microstrip-to-SIW transitions, the measured insertion loss is ≤ 1.5 dB over desired frequency band, with an amplitude and phase imbalance of ± 0.4 dB ± 4^°, respectively. Return loss performance of better than 15 dB is observed from 10 to 14 GHz, providing a wide relative bandwidth of around 33%. Measured results validate better performance compared to its SIW counterparts.