Ming-Sze Tong

Design and analysis of a stacked dual-frequency microstrip planar inverted-F antenna for mobile telephone handsets using the FDTD

We present the design of a microstrip, dual-frequency planar inverted-F antenna (DF-PIFA) for mobile telephone handsets that can concurrently work at two frequency bands, viz., the GSM and DCS 1800 systems, which operate at 0.9 and 1.8 GHz, respectively. A computer-aided design (CAD) tool, based on the non-uniform finite difference time domain (NU-FDTD) Maxwell solver, is employed to optimize the performance characteristics of the DF-PIFA, including the return loss, impedance match, frequency bandwidth and the far-field radiation pattern.

Study of Stratified Dielectric Slab Medium Structures Using Pseudo-spectral Time Domain (PSTD) Algorithm

A planar stratified dielectric slab medium, which is an interesting problem in optics and geophysics, is studied using a pseudo-spectral time-domain (PSTD) algorithm. Time domain electric fields and frequency domain propagation characteristics of both single and periodic dielectric slab-layer structures are analyzed. Results show that this method matches satisfactorily the Nyquist sampling theorem in terms of spatial discretization. By comparing the given results, it is found that the PSTD method outperforms the finite-difference time-domain (FDTD) method in general, especially in terms of the locations of critical frequencies and coarseness in spatial discretization.

Design and analysis of planar printed microwave and PBG filters using an FDTD method

In this paper, various planar printed microwave and photonic band-gap (PBG) filters have been designed and analyzed by applying the finite difference time domain method, together with an unsplit-anisotropic perfectly matched layer technique as treatments of boundary conditions. The implemented solver was first validated by comparing the computed data with those published in literature, and a good agreement was observed between the results. Then, based on the specified design criteria, various microwave and PBG filters were designed and analyzed, in which the theoretical predictions matched well with the computed results for the characteristics of the proposed filters.

Electromagnetic band‐gap (EBG) structures using combined inductive and capacitive elements and chirping‐and‐tapering technique

Purpose – To perform studies and comparisons on the electromagnetic band‐gap (EBG) structures, which are constructed by using a combination of inductive and capacitive elements printed on guided‐wave transmission lines, and by applying a chirping‐and‐tapering technique.Design/methodology/approach – An in‐house solver based on finite‐difference time‐domain (FDTD) method is adopted for analysis. Conventionally, EBG characteristics are formed by a series of perforations, considered as capacitive elements, on the ground plane(s). To enhance the performance, an additional inductive element is implemented, which is realized by narrowing the strip over the respective perforated regions. For further enhancement, a chirping‐and‐tapering technique is applied on the combined EBG structures for comparisons.Findings – Through scattering parameter analysis, it was found that the EBG structures using combined inductive and capacitive elements exhibit a band‐gap behavior superior to the ones built with only inductive or ...

Study on Wave Propagation and Boundary Absorption Performance using a Body-of-Revolution Finite-Difference Time-Domain (BOR-FDTD) Method

This paper presents some studies on electromagnetic wave propagation and absorption performance at boundary through an in-house developed solver based on a body-of-revolution finite-difference time-domain (BOR-FDTD) method. A generalized unsplit perfectly matched layer (U-PML) technique is incorporated with the solver. Time domain results on wave propagation through various structures, including parallel-plate disk, coaxial cable and general free-space, and frequency spectrum of the U-PML performance are presented. The U-PML shows a good absorption performance through flexibility in adjusting the layer thickness. The BOR-FDTD method offers tremendous savings in both computational memory and time when rotationally symmetric structures are analyzed

BOR-FDTD Studies on EBG Cylindrical Guided Structures

Cylindrical guided structures, such as coaxial lines or circular waveguides, have been widely adopted in microwave engineering, while study of electromagnetic band-gap (EBG) structures has become an interesting topic in the area. In this research, some studies are conducted through the EBG implemented on cylindrical guided structures, using a body-of- revolution finite difference time domain (BOR-FDTD) method. It is a two-dimensional (2-D) algorithm, applicable to analysis of cylindrical structures thanks to their axial symmetric properties. A periodic series of dielectric slabs are placed longitudinally along the guided structures for EBG formation. Clear band-gap properties are observed through the spectra of the scattering parameters. BOR-FDTD offers an alternative solution for such structures than a full 3D-FDTD analysis, as the former approach provides more efficient savings in terms of computational time and memory allocation.

Numerical analysis of PBG via structures using FDTD algorithm

Purpose – To study the photonic band‐gap (PBG) characteristics constructed by periodic conducting vias on various guided transmission‐line structures.Design/methodology/approach – The finite difference time domain (FDTD) method is adopted to analyze various PBG via structures. Conventionally, PBG characteristics on guided‐wave structures, such as microstrip lines or coplanar waveguides (CPW), are constructed through a series of perforations on the ground plane(s). PBG characteristics can, however, also be realized through periodic arrangements of conducting vias located on the respective ground planes.Findings – Through studies of the scattering parameters, it has been found that all analyzed PBG via structures exhibit strong band‐gap characteristics in a particular frequency range. Different harmonic patterns are also observed when the dimensional sizes of the conducting vias vary with respect to the PBG period.Research limitations/implications – Research has been mainly limited to study solely the PBG v...

Corrigendum to: Design and analysis of planar printed microwave and PBG filters using an FDTD method

School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, Singapore 639798 Department of Electrical Engineering, Swearingen Engineering Center, University of South Carolina, Columbia, SC 29208, USA Anhui Institute of Optics and Fine Mechanics, Hefei, China Department of Applied Physics, Hefei University of Technology, Hefei, China Army High Performing Computing Research Center, Institute of Technology, University of Minnesota, Minneapolis, MN 55415, USA EMI/Orsted, Technical University Denmark, Orstedplads, DK-2800 Kgs. Lyngby, Denmark Institute of Field Theory and High Frequency Engineering, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland

Analysis of photonic band‐gap structures in stratified medium

Purpose – To demonstrate the flexibility and advantages of a non‐uniform pseudo‐spectral time domain (nu‐PSTD) method through studies of the wave propagation characteristics on photonic band‐gap (PBG) structures in stratified mediumDesign/methodology/approach – A nu‐PSTD method is proposed in solving the Maxwells equations numerically. It expands the temporal derivatives using the finite differences, while it adopts the Fourier transform (FT) properties to expand the spatial derivatives in Maxwells equations. In addition, the method makes use of the chain‐rule property in calculus together with the transformed space technique in order to make the algorithm flexible in terms of non‐uniform spatial sampling.Findings – Through the studies of the wave propagation characteristics on PBG structures in stratified medium, it has been found that the proposed method retains excellent accuracy in the occasions where the spatial distributions contain step of up to five times larger than the original size, while sim...

Numerical studies of EBG structures printed on CPW lines

One of the current topics in computational electromagnetics is the study of electromagnetic band-gap (EBG) structures using planar printed transmission lines. In fact, structures using microstrip-line circuits have been comprehensively applied in recent years. However, studies involving transmission lines using the coplanar waveguide (CPW) have not been commonly conducted. In this paper, a number of EBG structures constructed on the CPWs are studied by using a well-known numerical method, the finite difference time domain (FDTD) method. Results show the band-stop filter behavior of these structures, and the computed results match generally well with the ones published in literature through solver validation. The proposed CPW EBG structures may be considered as alternatives to the conventional microstrip-line typed EBGs.