Muhammet Hilmi Nisanci

From Maxwell Garnett to Debye Model for Electromagnetic Simulation of Composite Dielectrics—Part II: Random Cylindrical Inclusions

A semianalytical approach to obtain an equivalent Debye frequency dependence of effective permittivity for biphasic materials with random spherical inclusions from the well-known Maxwell Garnett (MG) mixing rule is proposed. Different combinations of frequency characteristics of mixture phases (host and inclusions) are considered: when at least one of the phases is frequency independent; lossy (with dc conductivity); or with a known single-term Debye frequency dependence. The equivalent Debye models approximate very well the frequency characteristics obtained directly from MG mixing rule. In some cases, there is an exact match between the two models, and a good approximation is achieved in the other cases and is quantified by the feature selective validation technique. The parameters of the derived equivalent Debye model can be employed in full-wave time-domain numerical electromagnetic codes and tools. This will allow for efficient wideband modeling of complex electromagnetic structures containing composite materials with effective dielectric parameters obtained through MG mixing rule.

Optimum geometrical parameters for the EBG-based common mode filter design

This paper presents an efficient design procedure to obtain the physical dimensions of the electromagnetic bandgap (EBG) structure intended to filter common mode noise in high speed differential interconnects. The procedure is based on the concept of total inductance associated to the EBG geometry, and it offers wide flexibility for setting the geometrical EBG parameters. An optimum EBG design is studied investigating the relationships among the design parameters. This allows restricting the range of parameters that minimize the error between the achieved filter frequency and the nominal frequency. The study is carried out for several filtering frequency values and the results are validated by using full wave simulations. This paper also offers an example to synthesize the optimum EBG design for achieving a common mode filter at the desired frequency.

Practical EBG application to multilayer PCB: impact on signal integrity

In this paper, signal transmission performance of single ended and differential striplines between two parallel GND planes with embedded electromagnetic band gap (EBG) structure for noise isolation in high speed digital printed circuit boards (PCB) are studied. The performances in terms of |S11|, |S21|, |Sdd21| and |Scc21| are considered in function of the stack up cross section and position above the EBG. Practical considerations for the layout strategies are drawn.

Design of Homogeneous and Composite Materials From Shielding Effectiveness Specifications

A procedure to synthesize a suitable biphasic composite material from the given Shielding effectiveness (SE) specifications is proposed herein. In particular, this paper presents an analytic approach for calculating parameters of a Debye-like equivalent homogeneous material, which meets the SE requirements in given frequency range. Establishing the relationship of the SE with the intrinsic material and morphological properties of a composite will make it possible to effectively find an equivalent homogeneous lossy Debye-like material model, starting from the given SE frequency characteristic. The Maxwell Garnett mixing rule is used to synthesize a composite made by aligned cylindrical inclusions. A few examples of how this procedure works are presented; validation by time domain numerical simulations is provided.

Experimental validation of an 8 GHz EBG based common mode filter and impact of manufacturing uncertainties

Common mode noise associated to the differential signal propagation represents a major concern for crosstalk and EMI issues. The common mode filter based on electromagnetic band-gap (EBG) structures have been shown to be cost effective and easy to design, since they are made using the standard PCB technology. The coupling between the differential interconnect and the EBG cavity converts the energy associated to the common mode into the cavity resonant mode, thus reducing the common mode noise reaching the receiver. A simple design procedure is reviewed in this paper for a quick design, and it is applied to a 8 GHz filter. The filter is then manufactured on a 6 layer PCB and its performances are investigated through measurements both in frequency and time domain. The filter topology as well as the design procedure are validated through model-to-hardware correlation..

The prediction of the electric field level in the reverberation chamber depending on position of stirrer

This study presents nine modeling techniques within data mining process for the prediction of electric field level which depends on the positions of stirrer in the mode stirred reverberation chamber. These are Linear Regression (LR), Multi Layer Perceptron (MLP), Pace Regression (PR), KStar, Regression by discretization (RD), Random SubSpace (RS), M5P, RepTree and Decision Table models. Relations depending on frequency and position of stirrer have been carried out for the determination of electric field in the reverberation chamber. Obtained model results for each stirrer steps have been compared and the best model has been investigated. Results indicate that the use of derived formulation from these techniques will facilitate design and optimize of location of maxima (mode) and minima (null) of electric field in the reverberation chamber which a component of especially mode stirrer reverberation chamber test method.

Full-wave EMC simulations using Maxwell Garnett model for composites with cylindrical inclusions

Four different models for effective dielectric properties of biphasic composite containing random or aligned cylindrical inclusions are considered in this paper. These models are based on the Maxwell Garnett (MG) mixing rule. The effects of distribution and orientation of cylindrical inclusions in a composite material is studied. An equivalent averaged material with Debye-like frequency characteristics, suitable for time-domain full-wave numerical electromagnetic simulations is retrieved. This Debye model is derived from the Maxwell Garnett formulation. The numerical model test structure consists of a composite slab inserted in a rectangular waveguide. Simulations are run for the frequency range above the cut-off frequency of the fundamental mode TE10. The differences between the proposed models are quantified using the Feature Selection Validation (FSV) tool. The comparison of the models provides an insight on the effect of inclusion orientation and distribution.

Evaluation of dielectric permittivity for homogeneous materials from transmittance requirements

This paper presents a quick and efficient analytical approach to derive the electrical and geometrical properties of a medium that achieve a given transmittance (shielding) performances. The procedure is able to synthesize, according to the panel thickness, the frequency-dependent effective permittivity described in terms of a first order Debye model. The synthesis procedure is validated by comparing the specified transmittance to the performances of the synthesized medium simulated by a full-wave tool.

General regression neural network approach to prediction of electric field level in the reverberation chamber

This study presents an approach for the prediction of electric field level which depends on the positions of stirrer and frequency in the mode stirred reverberation chamber. A general regression neural network (GRNN) is used for prediction process. In order to show the system performance, feature selective validation (FSV) technique is given. The simulation results show that the predicted values of electrical field have been obtained with high accuracy. Thus, this technique will facilitate estimation of electric field level in the reverberation chamber which is component of especially mode stirrer reverberation chamber test method.