<p>A prephase synthesis method is proposed for
sidelobe 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 realizes equivalent amplitude
tailoring. Different from optimizing the prephase distribution, selection of
the numbers of 0 and π/2 prephases in
specific N regions is used to suppress the SLLs. Therefore, the parameters in the
optimization can be dramatically reduced from N<sup>2</sup> to N. The prephase
distribution is then designed based on the optimized number of prephases and a
symmetric matrix for SLL suppression in the whole space. The SLLs are further
suppressed by optimizing some of the unit cell states based on similar
equivalent amplitude tailoring. Simulation and measurement 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.</p>
Prephase-Based Equivalent Amplitude Tailoring for Low Sidelobe Levels of 1-Bit Phase-Only Control Metasurface under Plane Wave Incidence
