Wideband and High-Gain Millimeter-Wave Antenna Based on FSS Fabry–Perot Cavity

A novel wideband and high-gain millimeter-wave antenna is presented. The wide 3 dB gain bandwidth is achieved by using Fabry-Perot cavity (FPC) and printed ridge-gap waveguide technologies. The FPC is formed by placing a dual-layer partially reflective surface (PRS) above a slot antenna operating at 60 GHz and fed by a printed ridge-gap waveguide for surface-wave suppression. The PRS is based on a 2-D printed unit cell, the unit cell composed of two different frequency-selective surfaces (FSS) provides a positive phase gradient over the desired frequency range. The impedance bandwidth of the proposed antenna is 18.4%, from 55.4 to 66.6 GHz. Moreover, the 3 dB gain bandwidth is 12.5%, from 58.6 to 66.4 GHz. A maximum gain of 16.8 dB is achieved; this is about 12.2 dB over the gain of the slot antenna only. Consistent radiation patterns are achieved over the operating bandwidth. Experimental and numerical results are presented to justify the improved antenna performance. This communication, to the best of our knowledge, is the first one to utilize a dual-layer printed FSS-based superstrate at 60 GHz to enhance the radiation characteristics of a printed ridge-gap waveguide-fed slot antenna.