A Highly Selective Reflectarray Using ME Dipole Element With Gain-Filtering Characteristics

This communication proposes a highly selective 3 bit magnetoelectric (ME) dipole reflectarray (RA) based on the element's filtering gain response. A novel methodology for designing a gain-filtering RA antenna is presented by means of the selective ability of RA elements. The proposed RA element is a combination of ME dipole and split ring resonators (SRRs), which generate radiation nulls at 8.1 and 14 GHz. Thanks to the filtering functionality of the element, two non-phase-shifting areas with sharp roll-off are produced at lower and higher passband edges, meanwhile, the phase delay performs properly in the targeted band. Therefore, the gain-filtering functionality can be attained by just regulating the phase distribution under the condition of practically total reflection. At last, a 3 bit phase compensation strategy is exploited, and a gain-filtering RA antenna with a size of $8.4\lambda \times 8.4\lambda $ and a focal length of 0.64 times diameter is carried out. As compared to the reported works, the proposed RA antenna exhibits a wider 3 dB gain bandwidth, lower profile, and higher out-of-band gain suppression, by using the integrated element with gain-filtering characteristic.