Reconfigurable Reflectarray Antenna with Beam Steering Based on Metasurface

A reconfigurable reflectarray antenna with beam steering is presented in the thesis. The reflectarray system includes a reconfigurable reflecting surface and a feed antenna. The reflecting surface of the reflectarray antenna is composed of a periodic arrangement of unit cell elements where each cell has an embedded varactor for reconfigurability. The capacitance of varactors varies with the applied reverse bias voltage and it is used to control the phase distribution on the reflecting surface for realizing a reconfigurable system. By tuning the capacitance of the varactors, a reflected-phase tuning range of 300◦ is achieved by the proposed reflectarray element. The feed antenna of the reflectarray system is designed using a microstrip patch antenna with air gap included to increase the gain. The feed antenna has maximum gain of 9.8 dB and the main beam is set to be directed at the reflecting surface center. A mathematical method for feed radiation model is presented to analyze the aperture efficiency and directivity of the reflectarray system. The far-field radiation pattern result is obtained from a full-wave simulation using the commercial software CST Studio Suite. We demonstrate that the reflectarray system generates beam radiation along three different directions, as a proof of beam steering capability. The Full-wave result of the far-field simulations show that the maximum directivity is 18.5 dB which agrees favorably with the theoretical analysis.