A Compact Metasurface-Enabled Dual-Band Dual-Circularly Polarized Antenna Loaded With Complementary Split Ring Resonators

In this paper, the design and experimental validation of a novel miniaturized dual-band dual-circularly polarized (CP) metasurface (MS) antenna is reported. The proposed antenna is enabled by an engineered MS-based artificial ground that supports simultaneous dual-band functionality and dual-CP unidirectional radiation. The artificial ground is a highly truncated dual-layer MS containing an array of $2 \times 2$ unit cells. Each unit cell is comprised by a patch and a complementary split ring resonator (CSRR) printed on the top and bottom surfaces of the substrate, respectively. A printed feeding monopole antenna is integrated with the MS to form a low-profile dual-band dual-CP antenna with a thickness of $0.04{\lambda }_{0}$ , where ${\lambda }_{0}$ is the free-space wavelength at the first operational band. A dispersion analysis of the unit cell is carried out both analytically and numerically to illustrate the working principle of the proposed antenna. This reveals that the bianisotropic response and the orientation of the CSRRs jointly provide distinct dispersion behavior along two orthogonal directions of the dual-layer MS, enabling the desired dual-band dual-CP radiation. Moreover, the CSRRs also facilitate antenna miniaturization, yielding an overall footprint of only $0.33 \lambda _{0}\times 0.33\lambda _{0}$ . In order to verify the antenna design, a prototype is fabricated and tested, and strong agreement between simulated and measured results is observed, experimentally achieving a 50 MHz bandwidth, and a peak gain of 3.95 and 5.29 dBi at the two targeted bands with opposite handedness for the radiated waves.