scholarly journals Computing the T-matrix of a scattering object with multiple plane wave illuminations

2017 ◽  
Vol 8 ◽  
pp. 614-626 ◽  
Author(s):  
Martin Fruhnert ◽  
Ivan Fernandez-Corbaton ◽  
Vassilios Yannopapas ◽  
Carsten Rockstuhl
Keyword(s):  
Plane Waves ◽  
The Finite Element Method ◽  
Full Wave ◽  
Electric Dipoles ◽  
Complicated Object ◽  
T Matrix ◽  
Multiple Plane ◽  
Optical Nanostructures ◽  
Scattered Fields ◽  
Matrix Calculation

Given an arbitrarily complicated object, it is often difficult to say immediately how it interacts with a specific illumination. Optically small objects, e.g., spheres, can often be modeled as electric dipoles, but which multipole moments are excited for larger particles possessing a much more complicated shape? The T-matrix answers this question, as it contains the entire information about how an object interacts with any electromagnetic illumination. Moreover, a multitude of interesting properties can be derived from the T-matrix such as the scattering cross section for a specific illumination and information about symmetries of the object. Here, we present a method to calculate the T-matrix of an arbitrary object numerically, solely by illuminating it with multiple plane waves and analyzing the scattered fields. Calculating these fields is readily done by widely available tools. The finite element method is particularly advantageous, because it is fast and efficient. We demonstrate the T-matrix calculation at four examples of relevant optical nanostructures currently at the focus of research interest. We show the advantages of the method to obtain useful information, which is hard to access when relying solely on full wave solvers.

scholarly journals Ultrasonic Scattered Field Distribution of One and Two Cylindrical Solids with Phased Array Technique

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Xiaozhou Liu ◽  
Jian Ma ◽  
Haibin Wang ◽  
Sha Gao ◽  
Yifeng Li ◽  
...  
Keyword(s):  
Plane Wave ◽  
Field Distribution ◽  
Scattered Field ◽  
Phased Array ◽  
Simulation Analysis ◽  
Plane Waves ◽  
Theoretical Solution ◽  
Steel Matrix ◽  
Field Distributions ◽  
Scattered Fields

AbstractThe scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.

scholarly journals A Compact and Robust Technique for the Modeling and Parameter Extraction of Carbon Nanotube Field Effect Transistors

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2199
Author(s):  
Laura Falaschetti ◽  
Davide Mencarelli ◽  
Nicola Pelagalli ◽  
Paolo Crippa ◽  
Giorgio Biagetti ◽  
...  
Keyword(s):  
Field Effect ◽  
High Performance ◽  
Field Effect Transistors ◽  
Parameter Extraction ◽  
The Finite Element Method ◽  
Basic Step ◽  
Model Library ◽  
Full Wave ◽  
3D Geometry ◽  
Fitting Parameters

Carbon nanotubes field-effect transistors (CNTFETs) have been recently studied with great interest due to the intriguing properties of the material that, in turn, lead to remarkable properties of the charge transport of the device channel. Downstream of the full-wave simulations, the construction of equivalent device models becomes the basic step for the advanced design of high-performance CNTFET-based nanoelectronics circuits and systems. In this contribution, we introduce a strategy for deriving a compact model for a CNTFET that is based on the full-wave simulation of the 3D geometry by using the finite element method, followed by the derivation of a compact circuit model and extraction of equivalent parameters. We show examples of CNTFET simulations and extract from them the fitting parameters of the model. The aim is to achieve a fully functional description in Verilog-A language and create a model library for the SPICE-like simulator environment, in order to be used by IC designers.

Comparison of T-matrix calculation methods for scattering by cylinders in optical tweezers

2014 ◽  
Vol 39 (16) ◽  
pp. 4827 ◽  
Author(s):  
Xiaoqiong Qi ◽  
Timo A. Nieminen ◽  
Alexander B. Stilgoe ◽  
Vincent L. Y. Loke ◽  
Halina Rubinsztein-Dunlop
Keyword(s):  
Optical Tweezers ◽  
Calculation Methods ◽  
T Matrix ◽  
Matrix Calculation

The Transition Matrix Formalism for the Scattering of an Alluvium on an Elastic Half-Space

2007 ◽  
Author(s):  
Wen-I Liao ◽  
Tsung-Jen Teng ◽  
Shiang-Jung Wang
Keyword(s):  
Half Space ◽  
Transition Matrix ◽  
Plane Waves ◽  
Three Dimensional ◽  
Scattering Matrix ◽  
Elastic Half Space ◽  
Basis Functions ◽  
Matrix Formalism ◽  
T Matrix ◽  
Singular Wave

This paper develops the transition matrix formalism for scattering from an three-dimensional alluvium on an elastic half-space. Betti’s third identity is employed to establish orthogonality conditions among basis functions that are Lamb’s singular wave functions. The total displacements and associated tractions exterior and interior to the surface are expanded in a Rayleigh series. The boundary conditions are applied and the T-matrix is derived. A linear transformation is utilized to construct a set of orthogonal basis functions. The transformed T-matrix is related to the scattering matrix and it is shown that the scattering matrix is symmetric and unitary and that the T-matrix is symmetric. Typical numerical results obtained by incident plane waves for verification are presented.

Scattering of a Gaussian beam by an anisotropic-coated eccentric conducting circular cylinder

2020 ◽  
Vol 12 (9) ◽  
pp. 900-905
Author(s):  
Shi-Chun Mao ◽  
Zhen-Sen Wu ◽  
Zhaohui Zhang ◽  
Jiansen Gao ◽  
Lijuan Yang
Keyword(s):  
Gaussian Beam ◽  
Plane Waves ◽  
Approximate Expression ◽  
Transverse Magnetic ◽  
Addition Theorem ◽  
Electric Polarization ◽  
Electric Conductor ◽  
Solution Convergence ◽  
Local Coordinates ◽  
Scattered Fields

AbstractA solution to the problem of Gaussian beam scattering by a circular perfect electric conductor coated with eccentrically anisotropic media is presented. The incident Gaussian beam source is expanded as an approximate expression in the simple form with Taylor's series. The transmitted field in the anisotropically coated region is expressed as an infinite summation of Eigen plane waves with different polar angles. The unknown coefficients of the scattered fields are obtained with the aid of the boundary conditions. The addition theorem for cylindrical functions is applied to transfer from the local coordinates to the global ones. The infinite series can be truncated under the prerequisite of achieving the solution convergence. Only the case of transverse-electric polarization is discussed. The similar formulation of transverse-magnetic polarization can be obtained by adopting a similar method. Some numerical results are presented and discussed. The result is in agreement with that available as expected when the eccentric geometry comes to the concentric one.

scholarly journals Correction: Computing the T-matrix of a scattering object with multiple plane wave illuminations

2018 ◽  
Vol 9 ◽  
pp. 953-953
Author(s):  
Martin Fruhnert ◽  
Ivan Fernandez-Corbaton ◽  
Vassilios Yannopapas ◽  
Carsten Rockstuhl
Keyword(s):  
Plane Wave ◽  
T Matrix ◽  
Multiple Plane

scholarly journals Low-Cost Dielectric Substrate for Designing Low Profile Multiband Monopole Microstrip Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
M. R. Ahsan ◽  
M. T. Islam ◽  
M. Habib Ullah ◽  
H. Arshad ◽  
M. F. Mansor
Keyword(s):  
Microstrip Antenna ◽  
Dielectric Material ◽  
Low Cost ◽  
Cost Effective ◽  
Dielectric Substrate ◽  
The Finite Element Method ◽  
Radiation Patterns ◽  
Polymer Resin ◽  
Full Wave ◽  
Low Profile

This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm2radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53–2.89 GHz) and 440 MHz (3.47–3.91 GHz) for WiMAX and 1550 MHz (6.28–7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively.

scholarly journals Surface Susceptibilities as Compact Full-Wave Simulation Models of Fully-Reflective Volumetric Metasurfaces

2021 ◽  
Author(s):  
Ville Tiukuvaara ◽  
Tom J. Smy ◽  
Karim Achouri ◽  
Shulabh Gupta
Keyword(s):  
Computational Cost ◽  
Simulation Models ◽  
Arbitrary Field ◽  
Simulation Techniques ◽  
Full Wave ◽  
Unit Cells ◽  
Scattered Fields ◽  
Two Sides ◽  
Model Structures ◽  
High Computational Cost

<p>While metasurfaces (MSs) are constructed from deeply-subwavelength unit cells, they are generally electrically-large and full-wave simulations of the complete structure are computationally expensive. Thus, to reduce this high computational cost, non-uniform MSs can be modeled as zero-thickness boundaries, with sheets of electric and magnetic polarizations related to the fields by surface susceptibilities and the generalized sheet transition conditions (GSTCs). While these two-sided boundary conditions have been extensively studied for single sheets of resonant particles, it has not been shown if they can correctly model structures where the two sides are electrically isolated, such as a fully-reflective surface. In particular, we consider in this work whether the fields scattered from a fully reflective metasurface can be correctly predicted for arbitrary field illuminations, with the source placed on either side of the surface. In the process, we also show the mapping of a PEC sheet with a dielectric cover layer to bi-anisotropic susceptibilities. Finally, we demonstrate the use of the susceptibilities as compact models for use in various simulation techniques, with an illustrative example of a parabolic reflector, for which the scattered fields are correctly computed using a integral equation (IE) based solver.<br></p>

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