Broadband Spectral Numerical Green's Function for Electromagnetic Analysis of Inhomogeneous Objects

Hui H Gan,Tian Xia,Weng Cho Chew,Qi I Dai,Chao-Fu Wang

doi:10.1109/lawp.2020.2988475

Abstract

In this letter, we present a novel and efficient broadband spectral numerical Green's function (S-NGF) for inhomogeneous region. The proposed S-NGF is formulated in terms of the matrices that are obtained by the finite-element method (FEM). By performing modal analysis to FEM matrices, the proposed S-NGF is encapsulated by a series of resonant solenoidal modes where the operating frequency is embedded in the expansion coefficients. Besides, the convergence of the series of resonant solenoidal modes can be greatly accelerated by performing an extraction at one low wavenumber. The S-NGF can be rapidly reconstructed at different frequencies when it is integrated into the surface integral equation for inhomogeneous object modeling. The proposed algorithm is easy to implement, and well suited for the design and optimization of inhomogeneous electromagnetic structures, where fast solutions at massive frequencies are called for. The numerical examples demonstrate the efficiency and accuracy of the proposed scheme.

Highlights

D ESIGN of electromagnetic (EM) devices such as antennas, microwave circuits, and cavity resonators require one to carry out EM analysis for inhomogeneous media at massive frequencies, where efficient and accurate broadband algorithms are desired [1]–[3]
The proposed spectral-numerical Green’s function (S-NGF) of inhomogeneous media is encapsulated by a series of the eigenmode which are resulted from finite element method (FEM) discretization of an arbitrarily shaped and material-loaded region
We first study the accuracy and convergence characteristics of spectral numerical Green’s function (S-NGF) when it is truncated with a limited number of eigenmodes

Summary

INTRODUCTION

D ESIGN of electromagnetic (EM) devices such as antennas, microwave circuits, and cavity resonators require one to carry out EM analysis for inhomogeneous media at massive frequencies, where efficient and accurate broadband algorithms are desired [1]–[3]. The implementation of BI-RME seems more involved than the conventional MoM code for the analytical calculation of some tedious singular integrals [14] These schemes are limited to simple waveguide or cavity geometries where resonant modes are analytically available. The proposed spectral-numerical Green’s function (S-NGF) of inhomogeneous media is encapsulated by a series of the eigenmode which are resulted from FEM discretization of an arbitrarily shaped and material-loaded region. The contribution from the spurious direct current (dc) or irrotational modes is treated as a whole by solving a simple Poisson equation This reduced modal picture can be used for model order reduction of complicated resonating systems [15], [16]. We only consider lossless dielectric object, but the proposed S-NGF can be extended to lossy or magnetic material

NGF of Inhomogeneous Media

Spectral Numerical Green’s Function

NUMERICAL RESULTS

Accuracy of S-NGF

Antenna With Inhomogeneous Background

CONCLUSION