W-band tunable reflective type phase shifter based on waveguide-mounted RF MEMS

A novel concept for a continuously variable W-band phase shifter is proposed. It is based on a ridge waveguide resonator tuned by MEMS-actuated conductive fingers that interact with the fields beneath the ridge. The rotation of anti-parallel oriented MEMS conductive fingers of about half wavelength size realize a distributed interaction with the purposely structured waveguide ridge. In such a way, large transmission phase variations are obtained. By cascading an additional resonator and a waveguide short, a reflection type phase shifter is created with a single MEMS. For MEMS finger deflection angles between 0° and 7.5°, this device realizes reflection phase shift variation of 381° and a reflection coefficient magnitude of better than -1.65 dB at a frequency of 106.5 GHz. This corresponds to a figure of merit of 230°/dB.