Boundary restricted genetic algorithm for multi-layer equivalent dielectric parameters retrieval of artificial gradient structure

2020 ◽  
pp. 2150004
Author(s):  
Guo Shaojun ◽  
Shen Tongsheng ◽  
Zou Chunrong
Keyword(s):  
Genetic Algorithm ◽  
Dielectric Material ◽  
Field Analysis ◽  
Dielectric Parameter ◽  
Maximum Deviation ◽  
Gradient Structure ◽  
Dielectric Parameters ◽  
Boundary Parameter ◽  
Full Structure ◽  
S Curve

With the equivalent dielectric parameters of an artificial gradient structure consisting of a kind of dielectric material as inputs of FDTD multi-layer equivalent simulation, there are big nonuniform differences between the S-curve of retrieval methods and the corresponding full structure. In order to decease these differences, here, a boundary restricted genetic algorithm is proposed. In our method, Smith S method is employed to find the rough values of dielectric parameters, and at the same time, the up and low limit cases are introduced to calculate the boundary parameter values for each layer of the artificial structure and form the searching areas for genetic algorithm to get high-precision inversion of S-curve. The FDTD S-curve of the retrieval parameters and full structure of cone gradient and moth eye were performed experimentally, the maximum deviation of inversion S21 curves corresponding to the cone and moth eye with full structure is limited within 0.0028 and 0.0024 in the X-band (8–12[Formula: see text]GHz) range, respectively, which shows us the promising application of our method in dielectric parameter retrieval and may be helpful for electromagnetic field analysis.

Reflection Intensity Measurement for Dielectric Material Using a Microwave Single Probe and Its Electromagnetic Field Analysis

2006 ◽  
Vol 301 ◽  
pp. 125-128 ◽  
Author(s):  
Hirofumi Kakemoto ◽  
Satoshi Wada ◽  
Takaaki Tsurumi
Keyword(s):  
Electromagnetic Field ◽  
Simulation Model ◽  
Dielectric Material ◽  
Impedance Matching ◽  
Coaxial Cable ◽  
Field Analysis ◽  
Single Crystal Substrate ◽  
Single Probe ◽  
Crystal Substrate ◽  
Reflection Intensity

Microwave reflection intensity for microwave absorber, Cu-plate and Al2O3 (0001) single crystal substrate was measured from 8GHz to11GHz as a function of distance between single probe and sample at room temperature. The minimum reflection intensity was observed in the distance of 0.2mm between single probe and sample at 9.4GHz, although the reflection intensity was decreased with increasing distance in other measurement frequencies. The electromagnetic field analysis was hence carried out for simulation model that is defined with coaxial cable, probe and sample using finite differential time domain method. The reflection coefficient and impedance for simulation model were calculated, and compared to the experimental data. From results of electromagnetic analysis, the minimum point of reflection intensity was caused from an impedance matching.

scholarly journals NEW WAVEGUIDE METHOD FOR DIELECTRIC PARAMETER MEASUREMENT

2018 ◽  
pp. 33-38
Author(s):  
Andrey D. Grigoriev
Keyword(s):  
Frequency Band ◽  
Loss Tangent ◽  
Measurement Techniques ◽  
Microwave Frequency ◽  
Reflection Factor ◽  
Dielectric Parameter ◽  
Practical Implementation ◽  
Dielectric Parameters ◽  
Waveguide Section ◽  
Noise Component

Perfect knowledge of dielectric parameters is necessary for its application in various devices. In spite of the whole range of measurement techniques, their practical implementation in the microwave frequency band runs into some difficulties. This article describes a new method for nonmagnetic dielectrics permittivity and loss tangent measurement in the microwave frequency band. A dielectric specimen slab is placed in the short-circuited waveguide section normal to its axis and fills the whole cross-section of the waveguide at approximately quarter wavelength from its short-circuited endpoint. By means of the vector network analyzer the waveguide section reflection factor is measured. Objective function is de-termined as difference between calculated and measured module and phase of the reflection factor. Specific code for ob-jective function calculation and its minimization is worked out. Minimization of this function by varying dielectric parameters makes it possible to find real values of these parameters. The method needs no de-embedding and can be used with non-calibrated waveguide-to-coax transitions. Also it is less sensitive to the noise component of reflected signal. The testing results show that new method’s error does not exceed 0.2 % for relative permittivity and 1% for dielectric loss tangent.

scholarly journals Numerical stability of solitons waves through splices in quadratic optical media

2020 ◽  
Vol 42 ◽  
pp. e46881
Author(s):  
Camila Fogaça de Oliveira ◽  
Paulo Laerte Natti ◽  
Eliandro Rodrigues Cirilo ◽  
Neyva Maria Lopes Romeiro ◽  
Érica Regina Takano Natti
Keyword(s):  
Dielectric Properties ◽  
Optical Fibers ◽  
Numerical Stability ◽  
Propagation Distance ◽  
Numerical Approach ◽  
Dielectric Parameter ◽  
Dielectric Parameters ◽  
Gaussian Fluctuations ◽  
Optical Media ◽  
Complex Functions

The propagation of soliton waves is simulated through splices in quadratic optical media, in which fluctuations of dielectric parameters occur. A new numerical scheme was developed to solve the complex system of partial differential equations (PDE) that describes the problem. Our numerical approach to solve the complex problem was based on the mathematical theory of Taylor series of complex functions. In this context, we adapted the Finite Difference Method (FDM) to approximate derivatives of complex functions and resolve the algebraic system, which results from the discretization, implicitly, by means of the relaxation Gauss-Seidel method. The mathematical modeling of local fluctuations of dielectric properties of optical media was performed by Gaussian functions. By simulating soliton wave propagation in optical fibers with Gaussian fluctuations in their dielectric properties, it was observed that the perturbed soliton numerical solution presented higher sensitivity to fluctuations in the dielectric parameter β, a measure of the nonlinearity intensity in the fiber. In order to verify whether the fluctuations of β parameter in the splices of the optical media generate unstable solitons, the propagation of a soliton wave, subject to this perturbation, was simulated for large time intervals. Considering various geometric configurations and intensities of the fluctuations of parameter β, it was found that the perturbed soliton wave stabilizes, i.e., the amplitude of the wave oscillations decreases as the values of propagation distance increases. Therefore, the propagation of perturbed soliton wave presents numerical stability when subjected to local Gaussian fluctuations (perturbations) of the dielectric parameters of the optical media.

Method for Estimating the Charge Density Distribution on a Dielectric Surface

2017 ◽  
Vol 23 (3) ◽  
pp. 472-483
Author(s):  
Takuya Nakashima ◽  
Hiroyuki Suhara ◽  
Hidekazu Murata ◽  
Hiroshi Shimoyama
Keyword(s):  
Computer Simulation ◽  
Density Distribution ◽  
Charge Density ◽  
Dielectric Material ◽  
Three Dimensional ◽  
Dielectric Surface ◽  
Field Analysis ◽  
Charge Density Distribution ◽  
Organic Photoconductor ◽  
A Charge

AbstractHigh-quality color output from digital photocopiers and laser printers is in strong demand, motivating attempts to achieve fine dot reproducibility and stability. The resolution of a digital photocopier depends on the charge density distribution on the organic photoconductor surface; however, directly measuring the charge density distribution is impossible. In this study, we propose a new electron optical instrument that can rapidly measure the electrostatic latent image on an organic photoconductor surface, which is a dielectric surface, as well as a novel method to quantitatively estimate the charge density distribution on a dielectric surface by combining experimental data obtained from the apparatus via a computer simulation. In the computer simulation, an improved three-dimensional boundary charge density method (BCM) is used for electric field analysis in the vicinity of the dielectric material with a charge density distribution. This method enables us to estimate the profile and quantity of the charge density distribution on a dielectric surface with a resolution of the order of microns. Furthermore, the surface potential on the dielectric surface can be immediately calculated using the obtained charge density. This method enables the relation between the charge pattern on the organic photoconductor surface and toner particle behavior to be studied; an understanding regarding the same may lead to the development of a new generation of higher resolution photocopiers.

Effects of Dielectric Materials on Impedance Characteristics of Embedded Small Normal Mode Helical Antenna

2013 ◽  
Vol 446-447 ◽  
pp. 1059-1063 ◽  
Author(s):  
Yi Liao ◽  
Yuan Zhang ◽  
Zi Chang Liang ◽  
Jin Peng Fang ◽  
Wei Gao
Keyword(s):  
Wireless Communication ◽  
Resonant Frequency ◽  
Normal Mode ◽  
Finite Dimension ◽  
Dielectric Material ◽  
Complex Impedance ◽  
Dielectric Materials ◽  
Helical Antenna ◽  
Dielectric Parameters ◽  
Impedance Characteristics

The normal mode helical antenna (NMHA) is widely selected on RFID and wireless communication applications and often placed in a dielectric material for protection and miniaurization design. In this paper, the effects of dielectric materials with finite dimension on resonant frequency and impedance characteristics of embedded small NMHA were investigated. Three parameters related to the dielectric material were considered. Significant results were obtained by varying each one of these electrical dielectric parameters. It provides an effective guidance for designers to tune the antenna to desirable complex impedance when surroundded dielectric materials are employed.

CALCULATED DIELECTRIC PARAMETER OF BARIUM TITANATE-LEAD TITANATE COMPOSITES AS FUNCTIONS OF COMPOSITION AND FREQUENCY

1991 ◽  
Vol 05 (05) ◽  
pp. 357-363
Author(s):  
S.K. SARKAR
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Lead Titanate ◽  
Strength Loss ◽  
Dielectric Strength ◽  
Simplified Model ◽  
Connectivity Pattern ◽  
Dielectric Parameter ◽  
Dielectric Parameters ◽  
Titanate Lead

Some dielectric parameters, e.g. dielectric constant, resistivity, dielectric strength, loss tangent, saturation polarisation, coercive field, of barium titanate-lead titanate composites have been calculated as functions of composition and frequency, assuming a very simplified model and a 3–0 connectivity pattern. Most of the parameters have been found to vary linearly with composition at a given frequency.

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