Microwave variable delay line using a membrane impregnated with liquid crystal

A microwave variable delay line using a membrane impregnated with liquid crystal was newly fabricated. By employing this device configuration, the phase-shift response becomes fast independently of the liquid crystal thickness. Experimental results show that the phase-shift response time of 33 ms is obtained, which is two orders of magnitude faster than that of a conventional delay line. The new delay line also exhibits a 270-degree phase-shift and non-dispersive delay characteristics over a wide microwave-frequency range. Moreover, it is clarified that the phase-shift characteristics to a control voltage depend on the pore size of the membrane.