Jonas Ekman

Nonorthogonal PEEC formulation for time- and frequency-domain EM and circuit modeling

Electromagnetic solvers based on the partial element equivalent circuit (PEEC) approach have proven to be well suited for the solution of combined circuit and EM problems. The inclusion of all types of Spice circuit elements is possible. Due to this, the approach has been used in many different tools. Most of these solvers have been based on a rectangular or Manhattan representation of the geometries. In this paper, we systematically extend the PEEC formulation to nonorthogonal geometries since many practical EM problems require a more general formulation. Importantly, the model given in this paper is consistent with the classical PEEC model for rectangular geometries. Some examples illustrating the application of the approach are given for both the time and frequency domain.

Shielding Effectiveness Data on Commercial Thermoplastic Materials

Ten different commercially available conductive thermoplastic materials have been tested for near- and far-field shielding effectiveness (SE). Far-field SE was tested using a modified standard measurement technique to provide results comparable with the company-provided data. Further, housings of different thermoplastic materials were constructed and equipped with an electromagnetic interference (EMI) source to model a realistic near-field SE situation. The SE data up to 1 GHz is presented. Conductive thermoplastic materials with fillings of stainless steel fibers and nickel-coated carbon fibers were the two materials that offer the best far-field shielding performance. For the near-field shielding, two materials with filling of stainless steel fibers were the best performing ones. A thermoplastic with polycarbonate (PC) base and stainless steel content of 1.5 vol% showed the best combined far- and near-field shielding results

Susceptibility of sensor networks to intentional electromagnetic interference

It is reasonable to think that sensor networks might be part of society critical systems in the future. Therefor this paper discusses and shows the vulnerabilities of sensor networks to intentional electromagnetic interference (IEMI). Principle ways of sensor network IEMI is addressed and followed by a discussion on schemes for protection. Experimental results for both in-band and exband interference from low- and high- level sources is reported. It is obvious that more emphasis has to be put on sensor networks susceptibility to IEMI, and in particular more experimental data is needed

3D PEEC capacitance calculations

The partial element equivalent circuit (PEEC) method has shown to be useful in mixed circuit and electromagnetic analysis. In PEECs, the extensions from two to three dimensional modeling are mainly in the calculation of the partial self and mutual capacitive couplings. The considerable increase in problem size for 3D PEEC models results in a larger number of partial elements that has to be calculated. This results in excessive calculation times if the capacitive calculation routines are poorly constructed. In this paper it is shown that by using local reduction matrices for the capacitive calculations, the calculation time for PEEC model capacitance matrices can be decreased while keeping the accuracy.

Stability of PEEC models with respect to partial element accuracy

We examine the passivity and stability of quasi-static partial element equivalent circuit (PEEC) models. The impact of inaccuracies in the computed partial element values is considered as a possible source of time domain instabilities. Our analysis shows how existing partial element calculation routines, analytical and numerical, and the use of poor mesh generators can introduce large errors in partial element values. We also show how this affects the passivity and stability of the PEEC model. Theoretical constraints for passivity are derived which depend on accuracy of partial element values. The conditions are verified by performing practical PEEC model analysis.

A Delay-Rational Model of Lossy Multiconductor Transmission Lines With Frequency-Independent Per-Unit-Length Parameters

Cables, printed circuit boards, and VLSI interconnects are commonly modeled as multiconductor transmission lines. Models of electrically long transmission lines are memory and time consuming. In this paper, a robust and efficient algorithm for the generation of a delay-based model is presented. The impedance representation via the open-end matrix Z is analyzed. In particular, the rational formulation of Z in terms of poles and residues is exploited for both lossless and lossy cases. The delays of the lines are identified, and explicitly incorporated into the model. A model order reduction of the system is automatically performed, since only a limited number of poles and residues are included in the rational part of the model, whereas the high-frequency behavior is captured by means of closed expressions that account for the delays. The proposed method is applied to two relevant examples and validated through the comparison with reference methods. The time-domain solver is found to be more accurate and significantly faster than the one obtained from a pure-rational model.

A Measurement System for the Complex Far-Field of Physically Large Antenna Arrays Under Noisy Conditions Utilizing the Equivalent Electric Current Method

Precipitation in the form of snow or rain could severely degrade the performance of large antenna arrays, in particular if knowledge about the beam shape and pointing direction in absolute numbers is necessary. In this paper, a method of estimating the far-field of each individual antenna element using the equivalent electric current approach is presented. Both a least squares estimator and a Kalman filter was used to solve the resulting system of equation and their performance was compared. Simulation results shows that the estimated far-field for one antenna element is very accurate if there is no noise on the signal. During noisier conditions the Kalman filter gives less noisy results while the systematic errors are slightly larger compared to the least squares estimator.

Parallel Implementations of the PEEC Method

This paper presents a parallel implementation of a partial element equivalent circuit (PEEC) based electromagnetic modeling code. The parallelization is based on the GMM++ and ScaLAPACK packages. The parallel PEEC solver was successfully implemented and tested on several high performance computer systems. Large structures containing over 50 000 unknown current and voltage basis functions were successfully analyzed and memory, performance, and speedup results are presented. The numerical examples are both of orthogonal and nonorthogonal type with analysis in the time- and frequency- domain.

On characterizing artifacts observed in PEEC based modeling

This paper characterizes the different artifacts observed within time- and frequency- domain partial element equivalent circuit based electromagnetic modeling. The main focus is on frequency domain artifacts since time domain instabilities have been treated extensively in the literature. Guidelines and examples are given on how to suppress this type of artifact by showing correlation to PEEC model geometrical meshing and PEEC model complexity reduction.

A Hybrid PEEC–SPICE Method for Time-Domain Simulation of Mixed Nonlinear Circuits and Electromagnetic Problems

The simulation of mixed circuit and electromagnetic (EM) structures is of major interest in most EM applications. Many of the developed methods involve modifying a SPICE-like solver to incorporate an EM numerical method, or to extend the EM numerical method to handle the circuit components (e.g., diodes, transistors, etc.) by reimplementing their model definitions. A novel technique has been developed to simulate combined linear/nonlinear circuit and EM problems in time domain. This technique utilizes the partial element equivalent circuit method as the EM solver and employs OrCAD as the circuit solver. The link between the two solvers is established by defining the circuits connected to the EM structure as ports and approximating each ports current-voltage relations at each time point by a system of linear equations. To demonstrate the capability of the developed method, four structures are examined. Good agreement of the results shows the feasibility of the developed method to solve this type of mixed problems. Since OrCAD is used for the circuit simulations, the need to modify a SPICE-like solver or to reimplement the definitions of the circuit devices has been removed. On the other hand, by manipulating the system of equations and proper optimization techniques, an optimal solver can be achieved.