Double-layer broadband transmission metasurface and its application in low sidelobe antenna

This study proposes a double-layer metasurface which is capable of conducting independent amplitude and phase modulation for transmitting x-polarized waves under y-polarized incidence. The phase modulation is controlled by regulating the opening angle of the middle metal ring. Meanwhile, amplitude modulation is achieved by adjusting the rotation angle of the opening ring structure. The cross-polarized transmission response achieves complete phase and amplitude coverage and exhibits wideband characteristic with which a 3 dB gain bandwidth of 54.6% (5.4–9.5 GHz). The polarization isolation level is lower than −20 dB. In the wideband frequency range, the average sidelobe level of phase-only modulated metalens antenna is less than −20 dB with the lowest value of −22.5 dB, and the intermediate sidelobe level of amplitude-phase independent modulated metalens antenna is less than −25 dB with the lowest value of −27.4 dB. Both numerical simulated and experimental results verify that the proposed metalens antenna realizes a 4.8 dB averages of the sidelobe level suppression compared with the phase-only modulation metalens antenna. Holding strong anti-interference performance due to its superiority in polarization isolation level and side lobe level, the proposed antenna embraces broad application prospects in point-to-point communication systems in jamming environments.