A nematic liquid crystal tunable patch antenna

A design for a tunable, frequency-agile antenna is proposed. The structure consists of a microstrip patch and a nematic liquid crystal (N-LC) cell which serves as substrate. The N-LC cell is subject to an applied DC or low-frequency AC electric field. The strength of the bias field alters the tilt-angle of the directors, and thus, affects the relative dielectric tensor of the anisotropic material. The non-linear partial differential equation (PDE) governing the behavior of the directors´ field is coupled to Poisson´s equation for the electric potential in a non-homogeneous anisotropic medium. The coupled problem is solved iteratively using a finite difference (FD) numerical scheme. It is shown that the resonant frequency of the antenna can be altered using relatively low applied voltages. The obtained results are compared with measurements illustrating the potential use of LCs as tunable materials in microwave and millimeter-wave frequencies.