LAUSR

A modified model is presented in this letter to efficiently analyze the electromagnetic properties of the conformal capacitive frequency-selective surfaces (FSSs). By employing a dual set of quasi-orthogonal rooftop basis functions for the surface current distribution over the FSS conducting surface, the conditioning of the system matrix is significantly improved without decreasing the solution accuracy or increasing the computational costs. As a result, the iteration steps and CPU time are dramatically reduced in comparison with the conventional rooftop-expanded scheme. Besides, without subdividing the narrow side of the conducting cells of the FSS in the space discretization, the proposed model is also geometrical-adaptive and engineering-accordant, which results in a significant reduction of the number of unknowns compared to the conventional RWG-expanded scheme. Moreover, the multilevel fast multipole algorithm is employed to further improve the computational efficiency. Numerical experiments demonstrate the satisfactory accuracy and much higher efficiency of the proposed scheme.