Prephase-based Equivalent Amplitude Tailoring for Low Sidelobe Levels of 1-Bit Phase-Only Control Metasurface under Plane Wave Incidence

• Published in: IEEE transactions on antennas and propagation Vol. 70; no. 11; p. 1
• Main Authors: Yin, Jiexi, Wu, Qi, Wang, Haiming, Chen, Zhi Ning
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 1-bit; Amplitudes; Control systems; Equivalence; Mathematical analysis; Matrices (mathematics); Metasurfaces; Optimization; phase control; Planar arrays; Plane waves; reflective metasurface; sidelobe level (SLL); Sidelobe reduction; Sidelobes; Single-beam; Surface waves; Symmetric matrices; Transmission line matrix methods; Unit cell
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2022.3184968

A prephase synthesis method is proposed for side-lobe level (SLL) suppression of a 1-bit phase-only control metasurface under plane wave incidence. The array factor of the metasurface with N × N unit cells shows that controlling the number of prephases with varying values over the reflective surface can equivalently control the amplitude. Different from optimizing the prephase distribution, selection of the 0 and π/2 prephases in specific N regions is used to suppress the SLLs. Therefore, the number of parameters in the optimization can be dramatically reduced from N 2 to N . The prephase distribution is then designed based on the optimized number of prephases and a symmetric matrix for SLL suppression in the entire space. The SLLs are further suppressed by optimizing some of the unit cell states based on similar equivalent-amplitude tailoring. Simulations and measurements of a set of 1-bit reflective metasurfaces with 20 × 20 unit cells verify that the phase-only control metasurface realizes SLL suppression to -13 dB for multiple beam directions from -30 to 30 degrees with a 10-degree step under normal plane wave incidence.