Y.B. Gan

Perfectly matched layer-absorbing boundary condition for left-handed materials

The perfectly matched layer (PML) absorbing boundary condition (ABC) is extended to truncate the boundary of left-handed materials in the Finite-Difference Time-Domain (FDTD) simulation. The uniaxial material parameters are given in the frequency domain, and discretized in the FDTD update procedure by means of the Z-Transform technique. The effectiveness of the PML is demonstrated by numerical results.

General formulation of unconditionally stable ADI-FDTD method in linear dispersive media

The unconditionally stable alternating-direction-implicit-finite-difference time-domain (ADI-FDTD) method is used to model wave propagation in dispersive media. A formulation is presented by introducing the Z-transform method into the ADI-FDTD scheme to handle the frequency-dependent features of the media. This formulation is applicable to arbitrary dispersive media, and can be easily coded. Numerical results are compared to those based on the conventional FDTD method to show the efficiency of the proposed method.

Electromagnetic scattering by partially buried PEC cylinder at the dielectric rough surface interface: TM case

The Gaussian rough surface with the Gaussian correlation function is used to represent the statistical rough surface. Electromagnetic scattering from a partially buried perfectly electrically conducting (PEC) cylinder at the rough surface interface between two dielectric media is solved for the case of TM wave incidence using the method of moments with point matching. The effects of surface roughness and moisture content of the soil on the bistatic scattering cross section of the partially buried PEC objects at the rough surface interface are investigated using the Monte Carlo procedure.

Interaction of Electromagnetic Waves With 3-D Arbitrarily Shaped Homogeneous Chiral Targets in the Presence of a Lossy Half Space

The interaction of electromagnetic waves with an arbitrarily shaped three-dimensional (3-D) homogeneous chiral object located above a lossy half space is investigated using the method of moments (MoM) via the coupled mixed potential integral equations (MPIEs). Based on the surface equivalence principle, the equivalent surface electric and magnetic currents are used to replace the homogeneous chiral target in the presence of the half space. Two coupled MPIEs are developed for the unknown equivalent surface electric and magnetic currents by utilizing the continuity condition of the tangential total electric and magnetic field components on the chiral bodys surface. The well-known Galerkin procedure with Rao-Wilton-Glisson (RWG) basis functions is applied to solve this problem. The spatial domain half-space Greens functions are obtained from the corresponding spectral domain Greens functions via the discrete complex image method (DCIM) combined with the generalized-pencil of function (GPOF) technique. The reciprocity theorem is employed to calculate the far-zone scattered field. Numerical results are presented for characterizing electromagnetic scattering by a 3-D arbitrarily shaped homogenous chiral object located above a lossy half space so as to demonstrate the accuracy and efficiency of the proposed technique.

EFFECTIVE PROPERTIES OF FIBER COMPOSITE MATERIALS

The effective properties of fiber composite materials are considered in this paper. A simple semi-analytic-numerical method, based on the configurational average technique, the method of moment and the Monte Carlo method, is proposed to obtain the effective properties of a general thin composite slab. Analytical results for composite materials with low concentration of spherical inclusions agree well with that by the Maxwell-Garnett (M-G) theory, while the numerical results for fiber composite slab agree well with experimental results.

An accurate equivalent model for field iterative method

In this paper, the authors have found an equivalent model to set up accurate. formulae of the field iterative method (FIM) for interior scattering from cavity structures. The newly established FIM call be used to analyze scattering front various cavities with good convergence behaviour and accuracy. Numerical simulations for various cavity benchmarks, such as offset bend cavity, s-shaped cavity, double s-shaped cavity, annular cavity. and aerodynamic cavity structure, etc. have verified the accuracy and robustness of present formulation of the FIM.

Effective Permittivity Tensor of Composite Material With Aligned Spheroidal Inclusions

In our previous study, we have obtained the effective propagation vector of composite material with aligned spheroidal inclusions. Such composite material is found to be effectively anisotropic. It is necessary to retrieve the effective permittivity tensor to have a better understanding of the electromagnetic properties of such anisotropic material. Extraction of the effective permittivity tensor from the obtained effective wave number is considered in this paper. The problem is regarded as an inverse problem and is solved using the well-developed differential evolution strategy.

Comparative characteristics studies on on-chip single- and double-level square inductors

Detailed experimental investigations are carried out in this paper to show the inductance, Q-factor as well as resonant frequency of on-chip square single- and double-level inductors on silicon substrates. Based on the equivalent circuit model developed and the S-parameters measured using a de-embedding technique, inductances, Q-factors and resonant frequencies of these inductors are determined and compared with one another. Parametric studies are carried out to show the effects of both strip length and inner empty area on the coupling capacitance and resonant frequency of these inductors, and some scalable formulas are derived for extrapolating inductance and resonant frequency of other inductors. It is demonstrated that in the double-level cases very strong self-inductor resonance can take place with lower resonant frequency, and Q-factor is degraded rapidly.

Field iterative method for PEC cavity modeling

In this paper, the authors summarize the latest developments and extensions of the field iterative method (FIM) done in Temasek Laboratories and in collaboration with Professor Gary Thiele. The first topic discussed is the FlM based on an accurate equivalent model of a large perfect electric conductor (PEC) cavity. The second item discussed is the relaxed form of FIM, based on a simple equivalent model, which is accurate only for small incident angles and large PEC cavity. The third topic is the 3D implementation of the FIM. The accelerated version of the FIM, FAFFA-FIM, is also proposed to reduce the computational expenses of the FIM. These developments and extensions of the FIM provide an efficient approach to calculate the scattering from a PEC cavity structure.

Coupled IE-PO method for analysis of antenna radiation patterns in the presence of a large 3D radome

A method based on integral equation (IE) coupled with physical optics (PO) method is proposed for the analysis of antennas in the presence of a large three-dimensional (3D) dielectric radome. The electric field integral equation (EFIE) is applied to the conducting surfaces of the antenna array enclosed within a large 3D radome. Equivalent PO surface currents aree assumed on the radome walls induced by the near field radiation of the antenna. The PO currents are coupled back into the integral equation to account for the effects of the radome on the antenna. The resultant current distribution on the antenna obtained by this coupled IE-PO method is useful for computation of the antennas input impedance and radiation patterns with the effect of radome. As the PO method is applied to the large radome, no additional unknowns are needed, besides those defined on the surface of the antenna, leading to a substantial reduction in computational resources required. Numerical simulation showing the accuracy and efficiency of the coupled IE-PO method is presented.