Piecewise Surface Impedance Boundary Conditions by Combining Rytov's Perturbation Method and Level Set Technique

Abstract

Abstract-In this paper, we propose a computational method for constructing variable surface impedance, based on combining Rytov's perturbation method and level set technique. It is well-known that the choice of the most appropriate order of Rytov's expansion is important both for accuracy and implementation. By using level set method, we constructed a piecewise distribution of low-and high-order surface impedance boundary conditions on the surface of an arbitrarily shaped conductor. It is found that the proposed method is able to give good results both in terms of accuracy and implementation cost.

Computation of the RCS of 3d Conductor With Arbitrary Shape by Using Piecewise Sibc and Forward Backward Iterative Scheme

“…In our previous work [2], we have reported a numerical scheme combining Rytov's perturbation method and level set technique to construct a piecewise surface impedance for an arbitrarily shaped conductor. By using n level set functions ϕ 1≤i≤n , we can subdivide the conductor's surface into 2 n sub-regions Γ z i , 1 ≤ i ≤ 2 n , where each sub-region Γ z i is characterised by its own local SIBC Z i−1 ( J) [2].…”

“…By using n level set functions ϕ 1≤i≤n , we can subdivide the conductor's surface into 2 n sub-regions Γ z i , 1 ≤ i ≤ 2 n , where each sub-region Γ z i is characterised by its own local SIBC Z i−1 ( J) [2].…”

“…the method [2] leads to a SIBC discontinuity between adjacent regions which produces spurious edge effects when calculating the scattered fields, to circumvent this problem, we used forward-backward and quasiedge buffer iterative scheme. The introducing of local buffer area between adjacent sub-regions suppresses the singularities introduced by the abrupt termination of each sub-region and ensures stability and accuracy.…”

“…On the other hand, the improper use of low SIBC's orders degrades numerical accuracy, So, it will be interesting to apply a variable SIBC to have a good compromise between accuracy and implementation cost. In our previous work [2], we have reported a numerical method combining Rytov's perturbation method and level set technique to construct a piecewise surface impedance, we showed that by using level set technique, we could model an arbitrarily shaped conductor by a piecewise distribution of low-and high-order SIBCs. The proposed method [2] leads to a SIBC discontinuity between adjacent regions, which produces spurious edge effects when calculating the scattered fields.…”

“…In our previous work [2], we have reported a numerical method combining Rytov's perturbation method and level set technique to construct a piecewise surface impedance, we showed that by using level set technique, we could model an arbitrarily shaped conductor by a piecewise distribution of low-and high-order SIBCs. The proposed method [2] leads to a SIBC discontinuity between adjacent regions, which produces spurious edge effects when calculating the scattered fields. The method proposed in this article postulates the use of the forward-backward iterative scheme and the local "buffer regions" to suppress these unwanted effects and ensure stability of RCS computing.…”