Liquid crystal phase shifters at millimeter wave frequencies

We demonstrate an on-wafer liquid crystal phase shifter which has a tunable 0–300°/cm phase shift at 110 GHz. The results show no dispersion over the entire frequency range indicating a tunable “true time delay” of up to 2.5 ps/cm at all frequencies. The inherent losses in the liquid crystal are small, less than 1 dB/cm over the range of 1–110 GHz. The full tunability is achieved using small voltages, close to 10 V. We anticipate that one could achieve a phase shift of 600°/cm at 220 GHz.