Study of planar structure applying reciprocity technique combined with MGEC and analysis of discontinuity

The 3D structure electromagnetic computation presents several difficulties related to the volume mesh. In fact, the entire volume space must be taken into account even the smallest details. In this article, we propose a formulation based on the reciprocity theorem combined with the generalized equivalent circuit method to model a planar 3D structure with both coaxial and planar excitation. The major advantage of this formulation is the fact to reduce the computational volume into 2D ones in the discontinuity plane. In addition, we focused on the calculation of the discontinuity between the excitation source and the planar structure to determine the exact behavior of the electric coaxial excitation model. The obtained current density, electric field distributions, and the input impedance are presented and discussed in the following sections. An approximately good agreement of input impedance with those obtained by the simulator and measurement is shown.     

Discrimination des modes pour l’étude des discontinuités dans les circuits planaires

The study of the dispersion phenomena of a planar transmission line in boxed structure is very intricate. In this paper we will try to determine the origin of the different modes by varying the geometrical parameters of the structure at a given frequency. We will also study the complex modes and their effects on thee characterisation of the planar discontinuities.     

Propagation Constant of a Rectangular Waveguides Completely Full of Ferrite Magnetized Longitudinally

This paper is an analysis of rectangular waveguide completely full of ferrite magnetized longitudinally. The analysis is based on the formulation of the transverse operator method (TOM), followed by the application of the Galerkin method. We obtain an eigenvalue equation system. The propagation constant of some homogenous and anisotropic waveguide structures with ferrite has been obtained. The results presented here show that the transverse operator formulation is not only an elegant theoretical form, but also a powerful and efficient analysis method, it is useful to solve a number of the propagation problems in electromagnetic. One advantage of this method is that it presents a fast convergence. Numerical examples are given for different cases and compared with the published results. A good agreement is obtained.     

Coding graphene metasurface modeling using MoM‐GEC method for dynamic diffusion and scattering control at Terahertz range

In this article, we present an electromagnetic study of electrically programmable graphene‐based metasurface with individual scattering control. Our investigation is based on the method of moments combined with the generalized equivalent circuit (MoM‐GEC) approach. We show that, tuning the unit cell's conductivity leads to change its input impedance and scattering matrix. So, each unit cell of the metasurface exhibits' a dynamic phase response that can be switched between 0° and ?180° by controlling high transmission and total reflection states. Based on this feature, a 1‐bit coding metasurface consisting of discrete codes of “0” and “1” is used to synthesis 3D beams. Hence, tailorable anomalous reflection and diffusion are studied under normal incidence at a fixed frequency of 3.9 THz. This survey opens new opportunities in the domain of Terahertz beam engineering and security scanner applications.     

The design synthesis of periodical microstrip structures using adaptive genetic algorithm and a multiresolution MoM analysis

A multiresolution MoM analysis for the design of periodical microstrip structures is presented. An adaptive genetic algorithm (AGA) is introduced for the synthesis of planar structure designs that can have nearly any desired frequency response, and to optimize the choice of trial functions used on the MoM method. Results for a bandstop structure are presented to show the effectiveness of the proposed method.     

Electromagnetic wave propagation in anisotropic metamaterial waveguides

In this paper, we present the formalism of the transverse operator method (TOM). A rigorous study of propagation in anisotropic and multi‐layer medium using the tensor character of the permeability and permittivity is presented. With the application of the Galerkin method, the propagating modes in metallic rectangular waveguides filled with anisotropic metamaterial are exploited. The results are compared with those previously published and show a good agreement. The complex modes have been obtained. The advantages of the techniques used in this paper lie in the proper analytical formulation of the problem studied, on the one hand, and the speed of convergence, on the other hand. TOM offers a fast convergence of the propagation constant. This shows the effectiveness of our numerical model. As such, the formulation of the transverse operator could be a useful tool for microwave engineers. This type of materials known as metamaterial is widely used and needed by industries and information technology, especially in microwave and radiofrequency devices such as patch antennas, antennas waveguides, resonators, circulators, isolators, phase shifters, and filters. Copyright © 2014 John Wiley & Sons, Ltd.     

Absorbing boundary conditions for the FD‐TLM method : the perfectly matched layer and the one‐way equation technique

This paper investigates the absorbing boundary conditions for the frequency domain transmission line matrix method. Two approaches are presented, namely the perfectly matched layer (PML) technique and the one‐way wave equation. Concerning the PML technique, two‐dimensional and three‐dimensional transmission line matrix (TLM) nodes, already used in time domain, are exploited in frequency domain where a rigorous formulation of these PML–TLM nodes is presented. In addition, two types of one‐way wave operators are also transposed from time to frequency domain TLM approach: Taylor expansion and Higdon's boundary conditions. The simulation of a wideband matched load WR‐28 rectangular waveguide is presented for validation. Excellent results are obtained with a very thin PML layer. Results concerning one‐way operator techniques also show very good return loss performances. For instance, Higdon's boundary condition was extended beyond third‐order approximation, and a return loss better than 160 dB was obtained. Copyright © 2013 John Wiley & Sons, Ltd.     

Adaptive vectorial lifting concept for convolutive blind source separation

This paper describes a new multi-resolution approach for the blind separation of convolutive image mixtures in transform domain. The proposed method uses an Adaptive Vectorial case of Quincunx Lifting Scheme (AVQLS), based on wavelet decomposition, and a geometric unmixing algorithm. It proceeds in three steps: first, the mixed images are decomposed by AVQLS. Then, the unmixing algorithm is applied to the more relevant component to get a transformed estimate of the original images. An inverse transform is, thereafter, applied to obtain an estimate of the original images. Experiments carried out on medical images showed that the proposed method yields better separation results than many widely used blind source separation algorithms.     

Modeling of surface plasmon resonance nanobiosensor with the transverse resonance method

This article describes a new approach for the detection and identification of a molecular interaction in real‐time and non‐label with surface plasmon resonance (SPR). This approach is based on the transverse resonance method, modeling the nanobiosensor by an equivalent circuit that allows studying the dispersion characteristics of surface plasmon and the reflectivity. The results obtained from these two studies show that the dispersive study is very precise than the reflectivity one to determine the presence and nature of molecular interactions.