Realization and characterization of a 77 GHz reconfigurable liquid crystal reflectarray

A tunable microstrip reflectarray with beam reconfiguration capability at 77 GHz is presented. Tunablility is achieved by using anisotropic liquid crystal as RF-substrate, tunable by a biasing voltage below 15V. The reflector has been characterized by utilizing a lens setup forming a gaussian beam. The reflector properties has been extracted in terms of its reflected phase and magnitude: While it is possible to tune about 280. of phase, the associated losses are still quite high. Nevertheless, pattern measurements of the reflectarray showed distinct beam collimation towards different angles when appropriate DC control voltages are applied.