Computational electromagnetics

About: Computational electromagnetics is a research topic. Over the lifetime, 6412 publications have been published within this topic receiving 113727 citations. The topic is also known as: Electromagnetic field analysis.

Whole-System Electromagnetic Modeling for Microwave Tomography

Abstract: This letter presents a full-wave, whole-system modeling of microwave imaging tomography (MWT) systems to be used as the forward model in reconstruction (inverse) algorithms. The full geometry including antennas and their ports is simulated via a finite element method (FEM) approach. A new technique is used to compute the antenna operation in the system, which provides a general method to enforce the excitation as a specific modal distribution and to extract the voltage and current from the employed antenna. We report results for a complete microwave imaging (MWI) system with comparison between measured and simulated data.

Differences between the narrow-angle and wide-angle propagators in the split-step Fourier solution of the parabolic wave equation

Abstract: For tropospheric electromagnetic propagation, Maxwell's equations can be reduced to a parabolic wave equation, which is solved by marching over range steps. In each step, the solution is split into a product of three operators. The first and third account for atmospheric and surface variation, while the center operator propagates the field as though in vacuum. This center operator is the object of interest here. Older versions of the method used the narrow-angle propagator, while more recent versions use the wide-angle propagator. It was thought that the wide-angle propagator was entirely superior to the narrow-angle propagator, but some artifacts observed in experiments have led to the present investigation. The two propagators are examined numerically and analytically and found to exhibit subtle differences at large angles from the horizontal. This has required modifications to the way in which sources are created for starting the split-step solution. The narrow- and wide-angle propagators are also compared on two problems with analytic solutions to quantify the improvement of the wide-angle over the narrow-angle.

Comprehensive broad-band electromagnetic modeling of on-chip interconnects with a surface discretization-based generalized PEEC model

Abstract: A surface integral equation formalism is proposed for broad-band electromagnetic modeling of on-chip signal and power distribution networks. The discrete model is developed in the spirit of the partial element equivalent circuit (PEEC) model, which is extended with several attributes that lead to enhanced modeling versatility, modeling accuracy, and numerical solution robustness from dc to multigigahertz frequencies. Instead of the volumetric discretization model, which has dominated the PEEC-based schemes for handling the tall and slim cross sections of the on-chip wiring, the proposed model relies on a computationally more efficient conductor surface discretization. Key to the effectiveness and accuracy of the proposed surface discretization is the definition of a frequency- and position-dependent impedance quantity on the conductor surface. Its numerical computation over the frequency bandwidth of interest is expedited through the implementation of a complex frequency-hopping algorithm. The resulting effective surface impedance is combined with a mixed triangular/rectangular meshing of the conducting surfaces for the approximation of the surface electric current and charge densities. A systematic strategy for the identification of loops in the resulting discrete model is used to ensure a numerically stable mesh analysis-based PEEC formulation for on-chip signal and power distribution modeling with electromagnetic accuracy from dc to multigigahertz frequencies.

Modeling an electromagnetic telemetry system for signal transmission in oil fields

Abstract: Some finite element techniques for modeling an electromagnetic-based telemetry device known as the EM-MWD (electromagnetic measurement-while-drilling) used in oil fields are described. Results obtained from field tests at the test rig of GTI Gas Research Facility, Catoosa, OK, are compared with numerical results obtained using finite-element methods. The finite element technique used is based on the 2D-Axisymmetric H formulation.

$S$ -Parameter Sensitivities for Electromagnetic Optimization Based on Volume Field Solutions

Abstract: We propose a sensitivity analysis method that computes the S-parameter Jacobian from the volume E-field solutions in the frequency domain. The field solutions may be provided by any valid electromagnetic analysis. The computation is a post-process, which is independent from the simulator's grid, system equations, and discretization method. The sensitivity solver uses its own finite-difference grid and a sensitivity formula based on the finite-difference frequency-domain vector Helmholtz equation for the electric field. Its computational overhead is negligible in comparison with the simulation. We use the sensitivity solver in the gradient-based optimization of microwave structures. Significant reduction of the time required by the overall optimization process is achieved. In all design examples, the sensitivities are computed from the field solutions provided by a commercial finite-element simulator.