Design of Steerable Passive Reflectarray Using Non-uniform Elements for Main Beam and Side Lobe Level improvement

In this paper, a X-band beam steerable non-uniform reflectarray antenna is proposed. The -10dB power beamwidth and side lobe level of the proposed antenna are respectively 17° and -18dB which show significant improvement proportional to previous works. The beam steering is carried out with a small movement of a large element, i.e. the ground plane of the antenna. It is shown that the ground plane movement has negligible effect on the reflectarray phase characteristic, as a consequence of the proportionality between reflectarray phase distribution and element phase variation. This ensures that the distortion of far-field pattern is avoided. About ±10° tilt of antenna beam from the broadside is achieved with ±0.05λ ground movement. In the proposed structure beam steering capability is provided using passive elements which eliminates the problems of using active circuits such as bias difficulties, component losses and low power handling. After describing design procedure completely, the proposed antenna is simulated with an electromagnetic full-wave software and the results are validated.