his paper presents the design of a Ka-band phase shifter comprising a slow-wave structure that tightly wraps around three closely spaced MEMS capacitive switches. The switches are of proven design and reliability, except some switches have a gap in their stationary electrodes. This novel feature has negligible effect on electromechanical operation but provides another degree of freedom for simultaneous optimization of phase shift and impedance match. The design principle is validated through specially designed thin-film test structures. The results suggest that the present design is applicable to phase shifters of different sizes and resolutions with high performance, yield and reliability, but low cost and power consumption.