Cross-Shaped Interconnected Receiver–Transmitter Metasurface for a Circularly Polarized Fabry–Pérot Antenna

In this paper, we proposed a cross-shaped interconnected receiver–transmitter (RT) metasurface (MS) that was employed for a high-aperture-efficiency, high-gain, circularly polarized Fabry–Pérot (FP) antenna. The RT-MS unit cell consists of upper-layer cross-shaped patch and lower-layer squared patch that are connected by two metal-probes that cross the sandwiched middle metal-plane. The bottom patch receives electromagnetic wave, functioning as receiver, and transfers it to the top cross-shaped patch passing through the two mental probes. Through tuning the relative locations of the two probes, equal amplitude and 90° phase difference can be obtained, thereby achieving linear to circular polarization conversion performance, indicating that the MS has the ability of tuning transmission coefficients independently. Meanwhile, the MS is designed to present high reflectivity that high-gain property is obtained when forming a FP cavity. Then, an off-center coaxial patch antenna is applied as feeder due to its stable radiation performance. To further enhance the performance of the source antenna, an AMC structure is adopted to improving the radiation gain, efficiency and radiation directivity by suppressing surface wave loss. Meanwhile, the profile was also reduced. The linearly polarized wave emitting from the feeder multi-reflected in the FP cavity formed by MS superstrate and AMC structure, and then transmit it in phase to the space, thus a high-gain and CP radiation is achieved as final. The measurements demonstrate that the proposed RT-MS-based antenna perform a maximum gain of 18.7dBic at 9.4GHz with aperture efficiency of 76.7%, and a circular polarization bandwidth within 9.2-9.7GHz, while, the antenna owns a compact size of only $2.85\lambda _{0}\times 2.85\lambda _{0}$ . Thus, a novel RT-MS-based FP antenna exhibit a good radiation performance that can be a candidate in applying to communication and point-to-point links.