Design of High-gain Lens Antenna with Circular Polarization Conversion Based on Geometric Phase

In this paper, a Pancharatnam-Berry phase metasurface unit, owning circular polarization conversion and phase modulation functions, is designed. The unit has the advantages of subwavelength size, simple structure and no through-hole connections. The designed unit possesses high polarization conversion efficiency for any incident circularly polarized wave. When the resonator of the unit rotates, the transmitted electromagnetic wave acquires an extra phase of twice of the rotation angle. In the range of 0°~180°, as the resonator rotates in steps at 22.5°, a 3-bit phase quantization unit with transmission phase at 45° intervals is achieved, covering a phase range from 0°~360°. Based on the phase distribution theory of two-dimensional planar lenses, a novel high-gain lens antenna capable of dual-circular polarization conversion is designed, with a lens array surface size of 10λ×10λ (λ represents the wavelength corresponding to the antenna′s operating center frequency). Simulation results indicate that within the frequency range of 19.25 GHz~20.50 GHz, the designed lens antenna achieves a co-polarization gain above 26 dBi, a cross-polarization level below -20 dB, and an axial ratio below 2.2 dB. The peak gain at 19.75 GHz is 28.3 dBi, with a sidelobe level of -23.1 dBi and an aperture efficiency as high as 50.37%. The test results are generally consistent with the simulation results, validating the performances of the proposed Pancharatnam-Berry phase lens antenna.