Design of a Single-Layered Ka-Band Reflectarray Antenna Using ‘E’-shaped Elements for Gain Enhancement

This paper proposes the design of a reflectarray antenna composed of a single-layered periodic arrangement of microstrip elements constituting the reflectarray plane illuminated by a horn antenna operating at Ka-band. The reflectarray antenna is intended for operating at 19 GHz. The proposed unit cell of the reflectarray is a patch element which forms the shape of ‘E’. The optimization of the dimensions of the element is done to get a linear phase curve. The reflectarray plane consists of 81 elements. The designed horn antenna is placed at offset feed position to dodge the feed blockage. Proper positioning of the horn antenna for correct incident angle along with the selection of reflectarray element parameters gives the desired phase distribution on the reflectarray aperture surface. This results in the increase of the gain of horn antenna by 5.4 dB. The 3-dB beamwidth of the horn antenna has decreased from 48.6° to 12.1° in the E-plane and 49.3° to 13.2° in the H-plane, thus exhibiting more directional beam pattern due to the introduction of the reflectarray structure. Furthermore, the cross-polar radiation is significantly lower than the co-polar radiation for the proposed reflectarray antenna.