Design of Conformal Array of Rectangular Waveguide-Fed Metasurfaces

Abstract

We present a systematic design method for a cylindrical conformal array of rectangular waveguide-fed metasurfaces. The conformal metasurface consists of multiple curved rectangular waveguides loaded with metamaterial elements—electrically small apertures—inserted into the upper conducting walls of the waveguides. Each element radiates energy into free space to contribute to an overall radiation pattern. Thus, the geometry or electrical configuration of each of the elements needs to be tailored to generate a desired pattern. Generally, due to difficulties in modeling the effect of curvature, the design of conformal metasurface arrays has relied on full-wave simulations or experiments. In this study, we propose a design method utilizing the semianalytical model of a planar metasurface accounting for metamaterial elements’ locations and orientations over a curved surface. Although approximate, we demonstrate that the alteration along with the framework of dipolar modeling of planar elements can be used for the analysis of conformal arrays with small curvature. We then design a conformal array metasurface using the method combined with the covariance matrix adaptation evolution strategy (CMA-ES) optimizer. Through numerical simulations, we confirm the validity of the proposed design method. Applications include the design of metasurfaces for radar, communications, and imaging systems for mobile platforms.