W-band large-scale high-gain filtering reflectarray antenna

This article presents a W-band three-layer reflectarray antenna that can be easily fabricated using printed circuit board (PCB) process. The proposed reflectarray element is composed of substrate integrated waveguide (SIW) structure and slot-coupled patch. By controlling the length of SIW in each element, the compensation phases required for the reflectarray to generate focused beam at in-band frequencies are realized. However, at the out-of-band frequencies, the elements fail to provide the required compensation phases as the incident electromagnetic wave cannot couple to the SIW. Thus, filtering performance is realized. A circular aperture prototype reflectarray comprising of 5024 elements are employed to yield a high-gain narrow beam. The measured results show that the proposed reflectarray antenna attains a peak gain of 40.5 dB at 94 GHz with aperture efficiency of 41.3%, and out-of-band suppression higher than 22 dB.