A frequency-dependent WETD formulation for dispersive materials

A frequency dependent Whytney-element time-domain (WETD) method is proposed for the calculation of the interaction between transient electromagnetic fields and frequency dependent materials. The proposed formulation Is efficient since recursive convolution techniques are applied for the time domain implementation of the dispersive material characteristic. The method is suitable for the computation of the transient response in biological tissues, water and plasmas excited by pulse electromagnetic sources

Circuit-oriented FEM: Solution of circuit-field coupled problems by circuit equations

A general circuit-oriented, full-wave, finite-element method (FEM) is proposed to analyze the coupled problem between circuits and fields both in frequency and in time domains. The electromagnetic field problem is modeled by an equivalent electrical network obtained by the Whitney finite-element equations. The presence of circuit components in the field domain is easily taken into account introducing the lumped circuit components directly in the field equivalent electrical network. Simple test configurations are analyzed by a CAD circuit simulator to show the performances of the proposed circuit-oriented method

Full-wave analysis of shielded cable configurations by the FDTD method

A numerical method is proposed to model transients in a shielded cable embedded in a three-dimensional field domain by using the finite-difference time-domain (FDTD) method. The coaxial shielded cable is assumed to be a multiconductor transmission line (MTL). The in cell voltage and the current on the external shield surface are calculated by a full-wave method, while the core current and the core-to-shield voltage are analyzed by assuming the validity of the quasi-TEM propagation mode inside the shield. The internal and external shield surfaces are coupled by the transfer admittance and by the transfer impedance of the cable shield. The solution is obtained by the FDTD method combining the MTL equations with the field equations. The proposed time-domain method takes into account the frequency-dependent parameters of the cable conductors by recursive convolution techniques. The validation of the procedure is performed in simple test configurations

Circuit and numerical modeling of electrostatic discharge generators

This paper provides two accurate and efficient models of electrostatic discharge generators which permit to reproduce the discharge current in the contact mode, taking into account the load effect. The first model is based on a circuit approach and is suitable to be implemented in any commercial circuit simulator. The second model is based on the numerical solution of the field equations by using the commercial numerical-code microwave studio based on the finite-integration technique. The validation of the proposed circuit and numerical models is carried out by comparison with measurements

Edge-elements modeling of transmission lines in field domain by impedance network boundary conditions

Impedance network boundary conditions (INBCs) are applied to the ports of a transmission line (A) to simplify the finite-element-method modeling of a TL embedded in a field domain. The INBC-TL model is implemented in an edge-elements procedure to solve both time-harmonic and transient electromagnetic fields

Analysis of upsets and failures due to ESD by the FDTD-INBCs method

In this paper, a finite-difference time-domain (FDTD) model of an electrostatic discharge (ESD) event is developed. Analytical expressions for the field radiated during the ESD discharge phase have been determined to test the FDTD model of the strike arc. In order to take into account the electromagnetic field penetration through shielding structures, the conductive panels are efficiently modeled in the FDTD by the impedance network boundary conditions (INBCs). The FDTD-INBCs method avoids the huge amount of cells needed to model accurately the penetration in the traditional FDTD algorithm based on the utilization of the regular Yee grid. The method is applied to the analysis of ESD events in some configurations

Effects of the Dispersive Behaviour of Dielectric Substrates on the SPI

Actual printed circuit board configurations require either full-wave simulations or accurate analytical techniques for the analysis and the design of interconnects. This paper focuses on the effects of the dispersive behavior of dielectric substrates and on their simulation by means of new expressions giving a guidance on effective permittivity and per unit length (p.u.l.) parameters at the design stage

Using the LU Recombination Method to Extend the Application of Circuit-Oriented Finite Element Methods to Arbitrarily Low Frequencies

The circuit-oriented finite-element method (FEM) is a method that combines a finite-element field solver with a circuit analyzer and is suitable for analyzing electromagnetic field/circuit coupled problems. This paper describes a significant improvement to existing circuit-oriented FEMs that reduces the number of circuit elements and eliminates low-frequency stability problems. A modified LU recombination method is used to reformulate the original field-solver matrix equations. Circuits based on the reformulated equations are relatively insensitive to numerical errors and do not contain the small-value series resistors that circuit solvers are normally forced to add in order to guarantee a stable solution. Using this approach, the circuit-oriented FEM is capable of time-and/or frequency-domain simulations of problems containing linear or nonlinear lumped elements over a wide bandwidth. Examples are provided that demonstrate the ability of the new technique to model geometries from dc to several gigahertz in a single simulation

Full-Wave Model of Frequency-Dispersive Media With Debye Dispersion Relation by Circuit-Oriented FEM

Dispersive materials play an important role in a wide variety of applications (e.g., waveguides, antenna structures, integrated circuits, bioelectromagnetic applications). In this paper, a full-wave finite-element method (FEM-SPICE) technique for modeling dispersive materials is proposed. A finite-element formulation employing Whitney elements capable of analyzing electromagnetic geometries with dispersive media is described, and a Norton equivalent network is developed for each element. The overall network can be analyzed using a circuit simulator based on SPICE, and is suitable for both frequency- and time-domain analysis. This approach exploits the flexibility of finite-element mesh generation and computational efficiency of modern circuit simulators. Simple test configurations are analyzed to validate the proposed formulation

Magnetic field computation in a physically large domain with thin metallic shields

A three-dimensional edge element procedure is presented to analyze the magnetic field around thin shields embedded in a physically large domain. The shield region is eliminated from the computational domain and coupled boundary conditions named impedance network boundary conditions are imposed on the new boundary surfaces to take into account the field discontinuity produced by the eliminated shield. An experimental setup is built and the measured magnetic fields are compared to the results obtained by the proposed procedure