Dual-layer partially reflective surface antennas based on extended size unit cells for 60 GHz band WLAN/WPAN

In this study, planar dual-layer partially reflective surface, also known as frequency selective surface (FSS), antennas have been presented for 60 GHz band (57.24–65.88 GHz) wireless local area network (WLAN) and wireless personal area network (WPAN) applications. The FSS is excited through a microstrip patch antenna array of two elements designed at 63.72 GHz with return loss (S11) bandwidth and gain of 5.55 GHz and 13.2 dBi, respectively. Both the FSS unit cell and the feeding patch elements are set to be the same and they are designed based on the patch antenna size improvement method to convince the fabrication limitations imposed by the conventional printed circuit board etching process. Then three double layers FSS antennas have been designed with 2-elements, 12-elements and 24-elements in each FSS layer and measured gains of 15.6, 19.1 and 19.75 dBi, respectively, are achieved. It has also been found that when more layers and number of FSS elements are employed to improve the antenna gain, the overall S11 and gain bandwidth is reduced. In all the cases the measured results agreed well with the simulated results.