Linear-to-Circular Polarization Conversion Metasurface With Broadband Independent Amplitude/Phase Control for Sidelobe Suppression

This communication presents a novel independent phase and amplitude control metasurface to achieve broadband sidelobe suppression. The metasurface is a receiver and transmitter (R/T) structure with the ability to transform incoming linearly polarized (LP) waves to circularly polarized (CP) waves. At the bottom of the R/T-based element, a modified E-shaped patch is employed to receive the co-polarized LP waves, while the top layer has a similar configuration with connected arms for generating CP waves. A metallic via connects the top and bottom patches for power transmission. The transmission phase and amplitude can be independently controlled by tuning the orientations of patches on the top and bottom layers, respectively. As proof of concept, a transmitarray antenna based on the proposed metasurface is designed and fabricated to obtain high gain and low sidelobe performance. The measured results demonstrate that the designed antenna achieves a gain of 28.1 dBic at 60 GHz with a wide 3-dB gain bandwidth of 32.2%. The proposed transmissive metasurface holds great potential in radar and future wireless communication systems.