Random Rough Surface

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Leung Tsang - One of the best experts on this subject based on the ideXlab platform.

  • Electromagnetic computation in scattering of electromagnetic waves by Random Rough Surface and dense media in microwave remote sensing of land Surfaces
    Proceedings of the IEEE, 2013
    Co-Authors: Leung Tsang, Kung Hau Ding, Shaowu Huang, Xiaolan Xu
    Abstract:

    Active and passive microwave remote sensing has been used for monitoring the soil moisture and snow water equivalent. In the interactions of microwaves with bare soil, the effects are determined by scattering of electromagnetic waves by Random Rough Surfaces. In the interactions of microwaves with terrestrial snow, the effects are determined by volume scattering of dense media characterized by densely packed particles. In this paper, we review the electromagnetic full- wave simulations thatwe have conducted for such problems. In volume scattering problems, one needs many densely packed scatterers in a Randommediumsample to simulate the physical solutions. In Random Rough Surface scattering problems, one needsmany valleys and peaks in the sample Surface. In Random media and Rough Surface problems, the geometric character- izations of the media and computer generations of statistical samples of the media are also challenges besides electromag- netic computations. In the scattering of waves by soil Surfaces, we consider the soil to be a lossy dielectric medium. The ran- dom Rough Surface is characterized by Gaussian Random pro- cesses with exponential correlation functions. Surfaces of exponential correlation functions have fine-scale structures that cause significant radar backscattering in active microwave remote sensing. Fine-scale features also cause increase in emission in passive microwave remote sensing. We apply Monte Carlo simulations of solving full 3-DMaxwell’s equations for such a problem. A hybrid UV/PBTG/SMCG method is devel- oped to accelerate method of moment solutions. The results are illustrated for coherent waves and incoherent waves. We also illustrate bistatic scattering, backscattering, and emissivity which are signatures measured in microwave remote sensing. For the case of scattering by terrestrial snow, snow is a dense medium with densely packed ice grains. We have used two models: densely packed particles and bicontinuous media. For the case of densely packed particles, we used the Metropolis shuffling method to simulate the positions of particles. The particles are also allowed to have adhesive properties. The Foldy–Lax equations of multiple scattering are used to study scattering from the densely packed spherical particles. The results are illustrated for the coherent waves and incoherent waves. For the case of bicontinuous media, the method dev- eloped by Cahn is applied to construct the interfaces from a large number of stochastic sinusoidal waves with Random phases and directions. The volume scattering problem is then solved by using CGS–FFT. We illustrate the results of frequency and polarization dependence of such dense media scattering.

  • simulation and measurement correlation of Random Rough Surface effects in interconnects
    Electrical Performance of Electronic Packaging, 2012
    Co-Authors: Ruihua Ding, Leung Tsang, Henning Braunisch, Wenmo Chang
    Abstract:

    We study the effects of three dimensional (3D) Random Roughness on wave propagation in a parallel plate metallic waveguide with finite conductivity. The Surface Roughness is characterized as a Random process characterized by root mean square (rms) height, correlation length and power spectral density (PSD) function. The second order small perturbation method (SPM2) is applied to compute the coherent wave enhancement factors of absorption. A microstrip line structure is designed for validation of these enhancement factor results. Rough Surface height profiles are measured on the substrate and the PSD is extracted. With the PSD we obtain the enhancement factor for the specific Surface Roughness. The attenuation constant of the microstrip line with Rough Surface can be estimated using a field solution for a smooth Surface and the enhancement factor. The results for waveguides are also compared with the results obtained for a plane wave incident on a metal Surface with 3D Roughness. Comparison between the estimated and measured attenuation constant shows that the enhancement factor derived by SPM2 gives a better estimation than the standard Hammerstad and Bekkadal equation. The waveguide model gives more accurate enhancement factors than the plane wave model at frequencies above 20 GHz, especially for Rough Surfaces with rms heights larger than 2 μm.

  • Random Rough Surface effects in interconnects studied by small perturbation theory in waveguide model
    Electrical Performance of Electronic Packaging, 2011
    Co-Authors: Ruihua Ding, Leung Tsang, Henning Braunisch
    Abstract:

    We study the effects of Random Roughness on wave propagation in a parallel plate metallic waveguide with finite conductivity. The Rough Surface is three dimensional (3D) with Roughness heights varying in both horizontal directions. Integral equations are obtained from the extinction theorem formulated with layered medium Green's function. The second order small perturbation method is then applied to solve the integral equations. A closed form expression for the coherent wave is derived, which is expressed in terms of a three-fold Sommerfeld type integral due to the waveguide structure. Approximate methods are applied to calculate the Sommerfeld integral. The coherent wave enhancement factors of absorption are computed. The results for waveguides are also compared with the results obtained for a plane wave incident on a metal Surface with 3D Roughness. Results are illustrated for 3D Roughness with a variety of power spectra. It is shown that enhancement factors for a waveguide are larger than that of the plane wave case.

  • Random Rough Surface effects on wave propagation in interconnects
    IEEE Transactions on Advanced Packaging, 2010
    Co-Authors: Leung Tsang, Henning Braunisch, Ruihua Ding, Xiaoxiong Gu
    Abstract:

    To address the Rough Surface effects in high-speed interconnects on printed circuit boards (PCBs) and microelectronic packages, we study the electromagnetic wave propagation in a Rough Surface environment. In our model, the Rough Surface is characterized by a stochastic Random process with correlation function or spectral density. This paper reviews the analytical theory, numerical simulations and experimental results based on such a model. We describe the Rough Surface characterization and the extraction of Roughness parameters from 3D profile measurements. Initially we study the 2D case with the Rough Surface height function varying in only one horizontal direction and consider the case of plane wave incidence. Analytic second-order small perturbation method (SPM2) was used to obtain simple closed-form expressions for the absorption enhancement factor. The numerical transfer matrix (T-matrix) method and the method of moments (MoM) were also used. We next consider the case of the 3D problem with the Rough Surface height varying in both horizontal directions. We also used SPM2 to obtain a simple closed form expression for the enhancement factor. In interconnect problems, electromagnetic (EM) waves propagate in a guided wave environment. Thus, we next considered a waveguide model to study the effects of Random Roughness on wave propagation and compare with results from the plane wave formulation. Analytic SPM2 and numerical finite element method (FEM) with mode matching were used to obtain the enhancement factor. We also describe experimental results and correlation with the theoretical models. Finally, we explain how the enhancement factor concept used thRoughout lends itself to direct inclusion of Rough Surface effects in a wide variety of modeling problems.

  • a smfsia method for the electromagnetic scattering perfectly conducting Random Rough Surface
    2009
    Co-Authors: Chi Hou Chan, Leung Tsang
    Abstract:

    With the recent development of the sparse-matrix flat-Surface iterative approach (SMFSIA), the Monte Carlo simulations of scattering from two-dimensional (3-D scattering problem) Random Rough Surface problems have become much more efficient [l]. In SMFSIA, the iterative procedure involves multiplication of a very large square matrix with a column vector. In this paper, we show that this CPU time-consuming procedure can be replaced by the fast Fourier transform (FFT). A numerical example is given by investigating electromagnetic wave scattering using SMFSIA with the fast Fourier transform. This new method provides a faster solution time without sacrificing numerical accuracy. Electromagnetic scattering from a perfectly conducting Surface is based on the magnetic field integral equation.

Chi Hou Chan - One of the best experts on this subject based on the ideXlab platform.

  • a smfsia method for the electromagnetic scattering perfectly conducting Random Rough Surface
    2009
    Co-Authors: Chi Hou Chan, Leung Tsang
    Abstract:

    With the recent development of the sparse-matrix flat-Surface iterative approach (SMFSIA), the Monte Carlo simulations of scattering from two-dimensional (3-D scattering problem) Random Rough Surface problems have become much more efficient [l]. In SMFSIA, the iterative procedure involves multiplication of a very large square matrix with a column vector. In this paper, we show that this CPU time-consuming procedure can be replaced by the fast Fourier transform (FFT). A numerical example is given by investigating electromagnetic wave scattering using SMFSIA with the fast Fourier transform. This new method provides a faster solution time without sacrificing numerical accuracy. Electromagnetic scattering from a perfectly conducting Surface is based on the magnetic field integral equation.

  • Parallel analysis of electromagnetic scattering from Random Rough Surfaces
    Electronics Letters, 2003
    Co-Authors: Chi Hou Chan
    Abstract:

    An efficient approach for simulation of Random Rough Surface scattering is developed based on using a single integral equation formulation and a multilevel sparse-matrix canonical-grid method. Merits of the scheme are demonstrated using two wind-driven ocean Surfaces, one which is very Rough and the other large in size.

  • monte carlo simulations of large scale problems of Random Rough Surface scattering and applications to grazing incidence with the bmia canonical grid method
    IEEE Transactions on Antennas and Propagation, 1995
    Co-Authors: Leung Tsang, Chi Hou Chan, Kyung Pak, H Sangani
    Abstract:

    Scattering of a TE incident wave from a perfectly conducting one-dimensional Random Rough Surface is studied with the banded matrix iterative approach/canonical grid (BMIA/CAG) method. The BMIA/CAG is an improvement over the previous BMIA. The key idea of BMIA/CAG is that outside the near-field interaction, the rest of the interactions can be translated to a canonical grid by Taylor series expansion. The use of a flat Surface as a canonical grid for a Rough Surface facilitates the use of the fast Fourier transform for nonnear field interaction. The method can be used for Monte-Carlo simulations of Random Rough Surface problems with a large Surface length including all the coherent wave interactions within the entire Surface. We illustrate results up to a Surface length of 2500 wavelengths with 25000 Surface unknowns. The method is also applied to study scattering from Random Rough Surfaces at near-grazing incidence. The numerical examples illustrate the importance of using a large Surface length for some backscattering problems. >

  • studies of large scale Random Rough Surface problems with the sparse matrix flat Surface iterative approach
    International Geoscience and Remote Sensing Symposium, 1994
    Co-Authors: Leung Tsang, Chi Hou Chan
    Abstract:

    Scattering of the TE incident wave from a perfectly conducting Random Rough Surface is studied. First, the vector electromagnetic scattering from a two-dimensional Rough Surface with a Surface area of 81 square wavelengths is illustrated. Monte Carlo results show backscattering enhancement for the co-polarized component. Secondly, the TE scattering from a one-dimensional Random Rough Surface with a Gaussian Roughness spectrum is studied. Specifically, a grazing incident angle at 86/spl deg/ with a Surface length of 800 wavelengths is presented. Lastly, backscattering intensities from Gaussian and non-Gaussian Rough Surfaces are compared. Numerical results are illustrated as a function of rms height and slope. >

  • a smfsia method for the electromagnetic scattering from a two dimensional 3 d scattering problem perfectly conducting Random Rough Surface
    IEEE Antennas and Propagation Society International Symposium, 1994
    Co-Authors: Chi Hou Chan, Leung Tsang
    Abstract:

    With the development of the sparse-matrix flat-Surface iterative approach (SMFSIA), the Monte Carlo simulations of scattering from two-dimensional (3-D scattering problem) Random Rough Surface problems have become much more efficient. In SMFSIA, the iterative procedure involves multiplication of a very large square matrix with a column vector. The present authors show that this CPU time-consuming procedure can be replaced by the fast Fourier transform (FFT). A numerical example is given by investigating electromagnetic wave scattering using SMFSIA with the fast Fourier transform. This new method provides a faster solution time without sacrificing numerical accuracy. >

H Sangani - One of the best experts on this subject based on the ideXlab platform.

Akira Ishimaru - One of the best experts on this subject based on the ideXlab platform.

Xiaobang Xu - One of the best experts on this subject based on the ideXlab platform.

  • analysis of scattering from three dimensional objects buried below a Random Rough Surface by monte carlo mpstd method
    Progress in Electromagnetics Research B, 2013
    Co-Authors: Xiaobang Xu
    Abstract:

    This paper presents a Monte-Carlo multidomain pseu- dospectral time-domain (MPSTD) algorithm developed for the analy- sis of scattering from a three dimensional (3D) object buried below a Random Rough Surface separating two half spaces. In the development, special attention is paid to the 3D computation domain decomposition and subdomain mapping involving the Random Rough Surface as well as the subdomain patching along the Rough Surface. The Mote-Carlo MPSTD algorithm is then employed to determine the scattering of 3D objects of various shapes and electromagnetic properties; embedded in the lower half space with difierent permittivity and the Roughness of the Random Rough Surface may vary. Sample numerical results are presented, validated, and analyzed. ThRough the analysis, it is ob- served that the Roughness of the Random Rough Surface and the elec- tromagnetic properties of the lower half space can signiflcantly afiect the scattered signature of the buried object.

  • a monte carlo mpstd analysis of scattering from cylinders buried below a Random periodic Rough Surface
    Progress in Electromagnetics Research B, 2013
    Co-Authors: Xiaobang Xu
    Abstract:

    The analysis of scattering of objects buried below a Random Rough Surface is of practical interest. In reality, the Random Rough Surface may be of an extensive periodic structure. To deal with this more realistic situation, this paper presents a Monte-Carlo MPSTD numerical technique developed for investigating the scattering of a cylinder buried below a Random periodic Rough Surface. The computation model is formulated in two steps. In the flrst step, only the Random Rough Surface is considered and the periodic boundary condition (PBC) is enforced at the two ends of a period of the Rough Surface. Then, in the second step, a cylinder is placed below the Random Rough Surface and the interaction between the buried cylinder and the Rough Surface is taken into account. In each of the two steps, the flelds are computed employing the MPSTD algorithm developed in the authors' previous work. Sample numerical results are presented and validated.

  • scattering of object buried below Random Rough Surface a monte carlo pseudospectral time domain approach
    Electromagnetics, 2012
    Co-Authors: Haiyan Yang, Xiaobang Xu
    Abstract:

    Absract This article presents a numerical technique combining the multi-domain pseudospectral time-domain method and the Monte Carlo method for determining the scattering of an object buried below a Random Rough Surface separating two half-spaces. The numerical technique is employed to determine the scattering of a cylinder buried below a Random Rough Surface of finite length under various conditions. Sample numerical results are presented, validated, and analyzed. The results illustrate the significant impact of the Roughness of the Surface and the electromagnetic properties of the lower half-space on the scattered signature of the buried cylinder.

  • Scattering of Object Buried below Random Rough Surface—A Monte Carlo Pseudospectral Time-Domain Approach
    Electromagnetics, 2012
    Co-Authors: Haiyan Yang, Xiaobang Xu
    Abstract:

    Absract This article presents a numerical technique combining the multi-domain pseudospectral time-domain method and the Monte Carlo method for determining the scattering of an object buried below a Random Rough Surface separating two half-spaces. The numerical technique is employed to determine the scattering of a cylinder buried below a Random Rough Surface of finite length under various conditions. Sample numerical results are presented, validated, and analyzed. The results illustrate the significant impact of the Roughness of the Surface and the electromagnetic properties of the lower half-space on the scattered signature of the buried cylinder.