Metamaterial absorber-backed reflectarray antenna to improve a front-back ratio

A reflectarray antenna with a metamaterial (MM) absorber is presented to improve a front-back ratio by reducing a backlobe level. The presented reflectarray antenna is composed of a feed horn, a square patch reflectarray and a MM absorber which is based on a spilt-ring-cross resonator configuration. The improvement of the front-back ratio of the reflectarray antenna is achieved by combining the reflectarray with the MM absorber which is placed at the back of the reflectarray. To verify the improved front-back ratio, an onset reflectarray, an offset reflectarray and a MM absorber are fabricated and measured at 12 GHz and the radiation patterns of the onset and offset reflectarray antenna are presented according to the existence of the MM absorber.