VoxImp: Impedance Extraction Simulator for Voxelized Structures

An impedance extractor, called VoxImp, is proposed to compute the impedances of the structures discretized by voxels. VoxImp iteratively solves the volume-surface integral equations discretized by a carefully selected set of basis functions. During iterative solution, matrix-vector multiplications are accelerated by the fast Fourier transform, while the rapid convergence of the iterative solution at resonant frequencies is ensured by a novel sparse preconditioner. The memory requirement of the sparse preconditioner is reduced by a sparse LU decomposition obtained by a multifrontal algorithm with compressed frontal matrices. The overall memory requirement of the VoxImp is further reduced by the Tucker decomposition. VoxImp’s accuracy, efficiency, and capability are demonstrated through impedance extraction of various voxelized structures, including an RF coil array discretized by more than four million voxels and 15 million panels and analyzed on a commodity desktop computer.