A novel mapping approach to design FSS-based microwave absorbers for relaxed manufacturing tolerances

A novel mapping approach is proposed to relax the manufacturing tolerances of FSS-based microwave absorbers (MAs). A general reverse formulation for multilayered FSS-based MAs is first deduced, and then the design objective of reflection coefficient |Gamma| is mapped to a solution region of FSS's surface impedance Z(s). Together with HFSS, the base FSS configuration with maximum acceptable tolerance can be identified through optimization, where target parameters have the widest variations with Z(s) located in the solution regions. Compared with the conventional overdesign-before-verification strategy for tolerances, the proposed approach explicitly visualizes the design solutions and achieves the maximum acceptable tolerances without an empirical trial-and-error process. Finally, aiming at the standard manufacturing tolerance of sheet resistance R, the proposed approach is experimentally verified by a wideband absorber designed with a maximum R tolerance of +/- 21.4%. The measured result shows that the structure can easily fulfill the objective under the standard +/- 20% R tolerance.