A High-Gain and Wideband Filtering Millimeter-Wave Fabry–Pérot Cavity Antenna Enabled by High-Pass Source and Low-Pass Surface

This article introduces a filtering technique applied to the design of a wideband and high-gain Fabry–Pérot cavity (FPC) antenna for millimeter-wave (mm-wave) applications. The suggested method is to insert a low-pass frequency selective surface (FSS) into an FPC with intrinsic high-pass feeding source. By a combination of the two components (FSS and source), bandpass response can be generated effectively while maintaining high-gain performances realized by the proposed FPC. Both the proposed high-pass source and low-pass FSS exhibit wideband characteristics with tunable radiation nulls. Combined with a multimode resonant cavity structure, wideband performances can be achieved for the total antenna. For demonstration, a filtering FPC antenna operating at 30 GHz is designed, fabricated, and measured. The antenna consists of a low-pass feeding source, a modified ground, a partially reflective surface (PRS), and a low-pass FSS. Measured results show that the operating bandwidth of the antenna is from 22 to 30.5 GHz for the refection coefficient <inline-formula> <tex-math notation="LaTeX">$\le -10$ </tex-math></inline-formula> dB. It realizes a flat in- band gain with a peak gain of 19.5 dBi. The in- band radiation patterns are stable, whereas the out-of-band radiation suppression level is around 14 dB.