Multi-resolution time-domain modelling technique and its applications in electromagnetic band gap enhanced antennas

PhDNewly emerged Electromagnetic Band Gap (EBG) structures possess multiple frequency bands that prohibit wave propagation and such stop bands are basically determined by the periodicity of the structure. Such desirable features make EBG hybrid antenna an interesting topic. Traditional full-wave techniques lack the efficiency to fully cope with the complexity of these hybrid structures, since the periodical elements are often much smaller in size than the accompanying antenna components. The Haar wavelet based Multi-Resolution Time Domain (MRTD) technique provides improved numerical resolution over the conventional Finite-Difference Time-Domain (FDTD) method, as well as simplicity in formulation. One-dimensional, two-dimensional and three-dimensional level-one codes are developed to assist the numerical modelling of the hybrid EBG antennas. An explicit form of Perfectly Matched Layer (PML) configuration is proposed, proved and presented. As a generic approach, its extensions suit every single level of Haar wavelet functions. A source expansion scheme is proposed thereafter. The concept of a multi-band multi-layer EBG hybrid antenna is presented. The theoretical prediction of antenna resonances is achieved through an effective medium model. It has been verified via numerical simulations and measurements. The 3D MRTD code is later applied to simulate such a structure. In addition, EBG enhanced circularly polarized photonic patch antennas have been studied. It is demonstrated that split-resonant rings (SRRs) and the like in EBG antennas can lead to antenna gain enhancement, backward radiation reduction and harmonic suppression. Furthermore, a circularly polarized two-by-two antenna array with spiral EBG elements is presented. The spiral element with ground via is more compact in size than the traditional mushroom structure, which is proven very efficient in blocking unwanted surface wave. Hence it reduces the mutual coupling of the array antenna significantly

The High-Order Symplectic Finite-Difference Time-Domain Scheme

published_or_final_versio

Application of multiresolution analysis to the modeling of microwave and optical structures

A review of wavelet based techniques for the modeling of electromagnetic and optical structures is provided in this paper. Fundamental theoretical aspects of Multiresolution Analysis are mentioned along with mathematical properties of wavelet bases that lead to the construction of highly efficient numerical schemes and fast algorithms. Applications of such schemes in the field of time and frequency domain analysis of electromagnetic geometries are shown and the recently developed Multiresolution Time Domain technique is extensively presented. The analysis and evaluation of wavelet based techniques indicates their potential to provide fast and accurate solutions, thus broadening the limits of existing electromagnetic solvers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43340/1/11082_2004_Article_262994.pd

Adaptive transient solution of nonuniform multiconductor transmission lines using wavelets

Abstract—This paper presents a highly adaptive algorithm for the transient simulation of nonuniform interconnects loaded with arbitrary nonlinear and dynamic terminations. The discretization of the governing equations is obtained through a weak formula-tion using biorthogonal wavelet bases as trial and test functions. It is shown how the multiresolution properties of wavelets lead to very sparse approximations of the voltages and currents in typical transient analyzes. A simple yet effective time–space adaptive al-gorithm capable of selecting the minimal number of unknowns at each time iteration is described. Numerical results show the high degree of adaptivity of the proposed scheme. Index Terms—Electromagnetic (EM) transient analysis, multi-conductor transmission lines (TLs), wavelet transforms. I

Viability of Numerical Full-Wave Techniques in Telecommunication Channel Modelling

In telecommunication channel modelling the wavelength is small compared to the physical features of interest, therefore deterministic ray tracing techniques provide solutions that are more efficient, faster and still within time constraints than current numerical full-wave techniques. Solving fundamental Maxwell's equations is at the core of computational electrodynamics and best suited for modelling electrical field interactions with physical objects where characteristic dimensions of a computing domain is on the order of a few wavelengths in size. However, extreme communication speeds, wireless access points closer to the user and smaller pico and femto cells will require increased accuracy in predicting and planning wireless signals, testing the accuracy limits of the ray tracing methods. The increased computing capabilities and the demand for better characterization of communication channels that span smaller geographical areas make numerical full-wave techniques attractive alternative even for larger problems. The paper surveys ways of overcoming excessive time requirements of numerical full-wave techniques while providing acceptable channel modelling accuracy for the smallest radio cells and possibly wider. We identify several research paths that could lead to improved channel modelling, including numerical algorithm adaptations for large-scale problems, alternative finite-difference approaches, such as meshless methods, and dedicated parallel hardware, possibly as a realization of a dataflow machine

An Efficient MRTD Model for the Analysis of Crosstalk in CMOS-Driven Coupled Cu Interconnects

This paper presents an efficient wavelet based numerical method for analyzing functional and dynamic crosstalk of CMOS driven coupled copper (Cu) interconnects known as Multi-Resolution Time Domain (MRTD),wherein, the CMOS drivers are modeled using nth-power law model. The performance of the proposed MRTD method is evaluated through recursive simulations in HSPICE environment and compared with the conventional Finite Difference Time Domain (FDTD) method at 32-nm technology node for global interconnects of length 1mm, where the computations of the proposed model and conventional FDTD are carried out using MATLAB. For different number of test cases, the proposed MRTD method gives an average error of 0.14 % and 1.9 % for peak crosstalk noise and peak noise timing, respectively, with respect to HSPICE results. Also, the dynamic crosstalk noise on victim line of the proposed MRTD method are in close agreement with those of HSPICE. The results show the dominance of the proposed MRTD method over the conventional FDT method regarding accuracy. The proposed MRTD method is also extended for three-mutuallycoupled interconnect lines for crosstalk analysis, with an average error less than 1 % when compared to that of more than 3 % using the conventional FDTD method. Moreover, for the transient analysis, the MRTD method is more time efficient than HSPICE

Numerical modelling of optical micro-cavity ring resonators for WDM networks

Augmenting the level of integration for a lower cost and enhancing the performance of the optical devices have turned out to be the focus of many research studies in the last few decades. Many distinct approaches have been proposed in a significant number of researches in order to meet these demands. Optical planar waveguides stand as one of vital employed approach in many studies. Although, their low propagation loss, and low dispersion, they suffers from high power losses at sharp bends. For this reason, large radius of curvature is required in order to achieve high efficiency and compromise the high level of integration. For the purpose of this research, in this thesis different ways to improve the performance of optical microcavity ring resonators (MRRs) have been thoroughly investigated and new configurations have been proposed. The Multiresolution Time Domain (MRTD) technique was further developed and employed throughout this thesis as the main numerical modelling technique. The MRTD algorithm is used as a computer code. This code is developed and enhanced using self built Compaq Visual Fortran code. Creating the structure and Post-processing the obtained data is carried out using self built MATLAB code. The truncating layers used to surround the computational domain were Uniaxial Perfectly Matched Layers (UPML). The accuracy of this approach is demonstrated via the excellent agreement between the results obtained in literature using FDTD method and the results of MRTD. This thesis has focused on showing numerical efficiency of MRTD where the mesh size allowed or the total number of computed points is about half that used with FDTD. Furthermore, the MRR geometry parameters such as coupling gap size, microring radius of curvature, and waveguide width have been thoroughly studied in order to predict and optimise the device performance. This thesis also presents the model analysis results of a parallel-cascaded double-microcavity ring resonator (PDMRR). The analysis is mainly focus on the extraction of the resonant modes where the effect of different parameters of the structure on transmitted and coupled power is investigated. Also, accurate analysis of 2D coupled microcavity ring resonator based on slotted waveguides (SMRR) has been thoroughly carried out for the purpose of designing optical waveguide delay lines based on slotted ring resonator (SCROW). The SCROW presented in this thesis are newly designed to function according to the variation of the resonance coupling efficiency of a slotted ring resonators embedded between two parallel waveguides. The slot of the structures is filled with SiO2 and Air that cause the coupling efficiency to vary which in turn control both the group velocity and delay time of SCROW structures results from the changing the properties of the bent slotted waveguide modes which strongly depends on the slot’s position. Significant improvements on the quality factor and greater delay time have been achieved by introducing sub-wavelength-low-index slot into conventional waveguide