Compact Tunable Phase Shifter using Broadside-Coupled Structure with Wideband Coverage for Next Generation Communications Systems

A compact tunable phase shifter designed for K/Ka band applications, but covering frequencies from 12 GHz to 31 GHz, is presented. The tunable phase shifter is designed using a two-layer quarter-wavelength broadside-coupled structure. Specifically in K-band, it achieves a tunable phase range of 127° within the frequency band of 19 to 21 GHz, accompanied by a phase imbalance lower than ±1°. In the Ka-band frequency range of 29 to 31 GHz, the phase shifter exhibits a phase imbalance of only ±0.2°, with a tunable phase of 119°. The insertion loss remains below 1.5 dB across the entire operational bandwidth. The results underscore the potential of this tunable phase shifter for applications requiring precise phase control and minimal loss in microwave and millimeter-wave communications.