Eng-Kee Chua

Development of the Three-Dimensional Unconditionally Stable LOD-FDTD Method

A three-dimensional unconditionally-stable locally-one-dimensional finite-difference time-domain (LOD-FDTD) method is proposed and is proved unconditionally stable analytically. In it, the number of equations to be computed is the same as that with the conventional three-dimensional alternating direction implicit FDTD (ADI-FDTD) but with reduced arithmetic operations. The reduction in arithmetic operations leads to approximately 20% less computational time in comparisons with the ADI-FDTD method.

Application of integrated transmission line modeling and behavioural modeling on electromagnetic immunity synthesis

The paper presents an integrated electromagnetic immunity modeling, design and diagnosis system for EMI/EMC scenarios assessment and analysis of electronic devices/equipments. With extracting the intrinsic electric characteristic of PCB, a new modeling method which integrates transmission line modeling and behavioural modeling is proposed to be employed. The system is thus capable of modeling and analyzing electromagnetic interference therefore to evaluate the immunity level of electronic systems. It will also be customized so that it can be used for the design verification, parameter calculation and optimization.

Behavioral modeling for electromagnetic immunity analysis for electronic systems

This paper presents a system-level behavioural modeling method for electromagnetic immunity design and diagnosis of electronic devices/equipments by integrating with transmission line model. Through extracting the intrinsic behavioural characteristics of printed circuit board, one analytical model can be built for PCB which is conventionally described by using complicated transistor-level RLC circuit model or numerical model. The approach is capable of modeling and analyzing system-level conducted electromagnetic immunity.

Closed-form evaluation of the integration of Green’s function for method of moments

To overcome the Greenpsilas function singularity in electric field integral equations, closed-form expressions for the integration of Greenpsilas function are presented for different combinations of basis and test functions. Taylorpsilas series expansion of the Greenpsilas function is first obtained, then, integration of the expanded Greenpsilas function will be carried out. With proper choice of the number of expansion terms, required accuracy of the integration will be satisfied.

EM Performance of Conductive Composite Laminate Made of Nanostructured Materials for Aerospace Application

This paper presents the characterization of electro-magnetic (EM) performance of conductive composite laminate in consideration for aeronautic design. Novel nanocomposite resin was prepared by incorporating nanofillers into neat epoxy, resulting in remarkable improvement of its electrical conductivity. The planar structure of conductive composite laminate, which consists of 33 layers of woven fabric carbon fiber sandwiched in the nanocomposite, was then fabricated under the optimal conditions offering many times higher conductivity than the composite laminate using neat resin. Simulations of newly-developed composite laminate exposed to lightning strike were performed. The comparative studies show that conductive composite laminate provides better lightning protection property than composite laminate with epoxy resin. The simulated shielding effectiveness of the composite panel is in good agreement with measured results in both S and X microwave bands. The shielding effectiveness of the conductive composite laminate characterized at the frequency above 1 GHz is less than 10% different from that of conventional composite with copper wire mesh on the outer layer currently-used in aerospace industry. The result of this study shows promising aspect in the EM design using nanostructured composite laminate.

The stability analysis of the three-dimensional LOD-FDTD method

In this paper, we prove the unconditional stability of the three-dimensional locally one dimensional finite difference time domain (LOD-FDTD) method analytically for the first time. It is shown that the three-dimensional LOD-FDTD method is unconditionally stable. Numerical results are also presented to show the unconditional stability of the method.

Measurement of power distribution network impedance using an error analysis approach

In order to achieve power integrity (PI), power distribution network (PDN) impedance has been designed lower than calculated target impedance in frequency domain. However, with PDN impedance scaling down milliohm order, its measurement accuracy has been limited by the inevitable uncertainty from vector network analyzer (VNA). In this paper, we investigate the uncertainty effects in three impedance measurement methods using an error analysis approach. Impedance error rate is proposed as a function of variable uncertainty and the impedance of device under test (DUT), to represent the measurement accuracy. By analysis, we find that three methods have different accuracy for different DUT impedance ranges, and the appropriate method should be employed for different DUT measurements. Taking a fabricated power ground plane board (a special PDN) as case study, the measured results from three methods are compared with the simulated results from cavity model method and EM simulations in Computer Simulation Technology (CST) Microwave Studio, and the comparison results correlate well with our error analysis results. Its proven that the two-port method based on scattering parameter (S parameter) S21 performs best with highest accuracy for measuring the PDN impedance scaling down to milliohm order.

The Effects of Signal Trace's Termination on Ground Bounce and Common-Mode Radiation

Based on the method of moments, the ground bounce on any arbitrary printed circuit structure as well as the common-mode current on any conductor that attached to the printed circuit structure is predicted. The method of moments is applied to obtain the impedance matrix, which can be used to determine the unknown current vector and the inductance matrix. With the inductance matrix and current vector, the potential difference between any two adjacent nodes is predicted. The effects of the signal traces termination on ground bounce and common-mode radiation are discussed through numerical results.

Modeling common-mode radiation from high-speed PCB using method of moment

This paper present an approach to model the common-mode radiation from high-speed PCB using method of moment. By enforcing the boundary conditions for the Maxwells equations on the conductor and substrate of a PCB, a set of electric field integral equations (EFIEs) is formed. The common-mode (CM) current in the attached cable of a PCB is predicted numerically using the technique of method of moments (MM). With the predicted CM current, radiation from the cable can be calculated with ease. Good agreement with experimental results is demonstrated.

Evaluation of fibre weaving of substrate on differential microstrip using an analytical approach

Depending on the PCB fiber weave style, electrically long differential microstrip signal traces may introduce significant signal skew due to weave effect that deteriorates the signal quality. As closed-form expression for the effective permittivity that includes the weave effect is not readily available, full-wave method is often used to study the weave effect. As such, a novel analytical method is proposed in this paper to study the fibre weave effect in differential microstrip.