[show abstract][hide abstract] ABSTRACT: A multiresolution (MR) (wavelet) basis is employed in the method of moments (MoMs) analysis to achieve an efficient evaluation of the electromagnetic wave coupling inside metallic enclosures with arbitrary-shape openings. In this method, the electric field integral equation is solved on the surface of the enclosure discretized by triangular meshes. Using the MR meshing, different scales of the problem such as small apertures and narrow slots are represented directly into basis functions constructed by hierarchical sets of Rao-Wilton-Glisson expansion functions on a group of meshes yielded from subsequent refinements. As will be shown, the method results in highly sparse MoM matrices, which lead to fast convergence of iterative solvers. Hence, a remarkable reduction in the computational burden is achieved compared to the conventional RWG basis solution especially for the realistic enclosures with large number of apertures, used in the discipline of electromagnetic compatibility. Besides efficiency, the accuracy of the presented method is validated by a set of measurements conducted in an anechoic chamber.
IEEE Transactions on Electromagnetic Compatibility 03/2010; · 1.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: In the alternative current field measurement (ACFM) technique, the nonzero value of liftoff distance for the magnetic sensor acts as a low-pass filter on surface crack signals, causing errors in crack detection and sizing. We present a blind deconvolution algorithm for liftoff evaluation and surface crack signal restoration. The algorithm employs the available closed-form expressions for the distribution of electromagnetic fields at the metal surface in the vicinity of a crack. To examine the accuracy of the algorithm, we use the original and the restored signals for crack sizing by a wavelet network inversion method. We present simulated and experimental results to demonstrate the role of the proposed algorithm in improving the inversion process.
IEEE Transactions on Magnetics 09/2008; · 1.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: A fast method of moments (MoM) solution of surface electric field integral equation (EFIE) is employed to evaluate the electromagnetic wave coupling inside metallic enclosures, due to presence of arbitrary shape slots. In this paper, we propose an appropriate numerical integration technique in order to reduce the MoM impedance matrix calculation time without compromising accuracy. The technique is used to compute integrals resulting from MoM for the frequencies above the cavity first resonance. Within this frequency range, the wave penetration inside the enclosure is high and so one can avoid unnecessary high accuracy integrations. Regarding this new technique, the shielding effectiveness of an enclosure is evaluated efficiently in a wide range of frequency. The accuracy of the method is demonstrated by a number of examples.