Low insertion loss variable phase shifter for emerging millimeter-wave communication systems

This paper proposes a compact, low-loss, and low cost phase shifter for mmWave applications. The basic idea is perturbing the propagation constant of a CPW line by its loading with a high dielectric constant BLT ceramic. The phase shift is sensitive to the air gap between the CPW and the BLT sample. For a sample with a length of 3mm, a phase shift of 170° at 30GHz is obtained while the average insertion loss is less than 1.45dB with a variation of 1.1dB for the full range of phase shifts.