A Novel Broadband Partially Reflective Surface Superstrate for mm-Wave Printed Antennas

This paper presents a novel wideband partially reflective surface (PRS) unit cell to improve mm-wave printed antennas' radiation performances. The proposed PRS unit cell is constructed by two different layers separated by an air-gap, with only the bottom face of each layer has a copper pattern printed on it. On the bottom and top layers of the PRS unit cell, a capacitive patch, and an inductive patch with a square-slot-loaded patch (SSLP) are printed, respectively. The unit cell exhibits a broadband positive phase gradient of the reflection coefficient with a high reflectivity around 62 GHz. As a superstrate above printed antennas, the PRS layers can be very useful in improving the radiation gain performance of mm-wave antennas in the considered band around 60 GHz.