Analysis of design of broadband checkerboard metasurfaces for rcs reduction

Abstract

This thesis broadly focuses on the following topics: (i) Methods and designs for realizing broadband checkerboard metasurface (CMS) structures for the RCS reduction of flat metal targets(ii) Investigations on the relationship between mutual coupling and array size and their collective impact on the RCS reduction bandwidth of CMS. The research starts with investigations on further enhancing the RCS reduction bandwidth of already reported broadband CMS using an optimization algorithm. In this process, an approach linking CST and MATLAB is used to design broadband elements that construct the CMS. The conventional criteria to obtain 10 dB RCS reduction using CMS is to maintain a phase deviation of 180±37° between the two-unit cells that construct the CMS. Two pairs of unit cells, namely (i) square-circle pair and (ii) Jerusalem cross small-large, already reported in the literature, are chosen, and the optimization routine is applied, which results in an increase in the bandwidth by about 5%. These are designed on Rogers 5880 substrate of thickness 6.75 mm. Considering the high cost of the substrate and also with the aim of exploring other configurations, an air gap of 5 mm is introduced with a Taconic substrate of 1.57 mm thickness. This altered structure further enhances the RCS reduction bandwidth, and this configuration of the CMSs is fabricated and tested. Despite introducing the air gap, the cost remains high. newline