Phase tunability of reflectarray patch elements using tunable dielectric substrate of nematic liquid crystal

There has been much interest recently in developing reconfigurable reflectarray antenna for tunable microwave applications. Liquid crystal (LC) has been given much attention due to its dielectric anisotropy property which allows the change in the frequency and hence the phase of reflection. In this paper, the phase tunability of the periodic array using K15 nematic liquid crystal as the dielectric permittivity is presented. Simulated and experimental results at X-band are used to compare the plane wave scattering parameter from a two patch reflectarray cell of 500 μm. A tunable dynamic phase range of 221° is achieved over a broad band of 220 MHz which also gives a tunability of 2.2%.