Search

An efficient B-spline curvature-based reflector shape synthesis technique for generating a continental US (CONUS) beam pattern is presented. The approach is based on representing a reflector as a set of curves that can be modified to alter the reflector’s shape. Instead of directly optimizing the curves as done in other commercial software packages, the curvature is evaluated and represented using B-spline polynomials. The control points of each spline curve are defined as optimization variables, which generate new curvature profiles at each iteration. The set of curves with the corresponding curvature is synthesized using the natural equation method and is then used to construct the reflector surface. This two-step process of first optimizing the curvature and then reconstructing a reflector surface greatly facilitates the ability to impose constraints on surface curvature arising from the choice of the manufacturing process. Furthermore, no significant degradation in the convergence behavior was observed when including curvature bounds in the cost function. This makes the approach very attractive when compared to existing methods. In addition, this method can be applied to arbitrary reflector configurations of interest and be paired with any optimization method. The accuracy and validity of the proposed method are verified by multiple application examples.

Coding metasurfaces (CMSs) rely on the proper tiling of two or more kinds of complementary unit cells within an array to enable phase cancellation and corresponding destructive interference thereby reducing the radar cross-section (RCS) of a given scatterer. Typically, these unit cells are planar and inherently limited in their field of view (FoV). This work demonstrates that breaking this traditional unit cell design paradigm in favor of novel 3-D meta-volumes enables both broadband and wide-FoV RCS reduction. Further, this work introduces a modified genetic algorithm (GA) framework for simultaneously tailoring the reflection phase of multiple unit cells to achieve the best composite response. By applying these identical pair-optimization strategies, it is shown that 3-D unit cells outperform their 2-D counterparts of the same lateral size in terms of both the fractional bandwidth (FBW) and FoV. One exemplary 3-D solution purely improves the $H_{\mathrm {x}}$ response with FBW exceeding 75% across a full 70° FoV. A second 3-D solution provides an improved $E_{\mathrm {x}}$ polarization response with a near 70% FBW at 45° and up to 75% FBW at 70° for the $H_{\mathrm {x}}$ polarization at the expense of reduced FBW close to 50% for incidence angles less than 45°.