Low-profile circularly polarized Fabry-Perot antenna fed by air-coupling microstrip patch

A circularly polarized Fabry-Perot resonator (FPR) antenna is presented in this paper, which is feed by air-coupled patch antenna. The circular polarization wave is excited by an equilateral triangle patch and cross-shaped gap on the metal ground plane. The FPR resonator consists of a partially reflective surface (PRS) formed by rhombus slot frequency selective surface (FSS) and metal ground plane. The profile of the prototype has reduced to nearly a quarter of a wavelength. The measured results and simulated results are approximately accordant and a peak gain of 18.7 dB can be achieved, which is higher than that of common single-feed patch antennas and the proposed antenna has a common frequency bandwidth of 3.5% for S11 ≤ -10dB, gain-drop ≤ 3dB, and axial ratio ≤ 3dB.