Fabry-Pérot Resonator Antenna in Equivalent-Medium Metamaterials

In this paper, a wideband Fabry-Perot resonator antenna (FPRA) is proposed. An optimized partially reflective surface (PRS) with transverse permittivity gradient (TPG) composed of four non-rotationally symmetric sections is employed in the design of the antenna. The use of non-rotationally symmetric PRS results in more than 31% improvement of the 3-dB gain bandwidth, compared with the traditional rotationally symmetric PRS. Furthermore, two types of non-resonant metamaterials (metallic-ring and etching-hole unit cells) are used to implement the equivalent permittivity of PRS. In this way, the equivalent permittivity value covers a broad range (3.5-9.5) for the same dielectric. As a result, the restrictions imposed by the use of only commercially available dielectrics and the errors that occur during the fabrication and assembly progress of different materials can be avoided. The primary radiator of FPRA is a double-ridge waveguide horn, which ensures wideband antenna operation. An FPRA prototype is fabricated and measured, which exhibits a broad bandwidth (5.2–11.5 GHz) with the return loss |S11| less than -10 dB. The measured 3-dB gain bandwidth is 73.8% (in the frequency range 5.3-11.5 GHz) with a peak gain of 17.1 dBi at 7.8 GHz.