Tunable band-pass filter based on Liquid Crystal

This paper presents a design study of a tunable band-pass filter. The tunability is achieved by using Liquid Crystal (LC) as a tunable dielectric. The respective three-pole filter is designed to have a center frequency of 20 GHz. It is shown that the center frequency of the designed filter can be shifted by approx. 2 GHz. The device is fabricated using a glass-LC-glass sandwich structure with a total thickness of 600 μm. The lateral dimensions of a single filter structure are 9 × 4 mm.