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This paper analyses the problem of coupling multiple angular regions in spectral domain by using the generalized Wiener-Hopf technique. The paper introduces also the technique to obtain a solution of the problem by reducing the factorization problem to Fredholm integral equation. We present a test case constituted by two PEC wedges.
We consider propagation of surface TM waves in a circular dielectric waveguide filled with nonlinear (Kerr nonlinearity) multilayered inhomogeneous medium. Each layer is characterized by a specific value of the nonlinearity coefficient α. Analysis is reduced to solving a nonlinear transmission eigenvalue problem for an ordinary differential equation; eigenvalues of the problem correspond to propagation...
We study the relation between quasi-normal modes (QNMs) and transmission resonances (TRs) in one-dimensional (1D) disordered systems. We show that while each maximum in the transmission coefficient is always related to a QNM, the reverse statement is not necessarily correct. There exists an intermediate state, where only part of the QNMs are localized and provide a resonant transmission. The rest...
A recent communication provided a model for the transmittance between two antennas supporting Orbital Angular Momentum modes. That formulation involved a single integral along the radial spectral coordinate. That approach actually also applies to any pair of apertures supporting arbitrary distributions. Asymptotically, for far field conditions, an analytical expression has been developed, as a power...
“After more than a half century of Anderson localization, the subject is more alive than ever” [1]. In acoustics, the first observation of sound localization in three dimensions has been reported in a random elastic network of aluminum beads, a so-called “mesoglass” [2]. Here, we propose to investigate this complex wave phenomenon by studying ultrasonic wave transport through in situ experiments performed...
The transmission of a single rectangular hole filled with uniaxial anisotropy is investigated. After plane wave passes through the hole, there can be resonances at different frequencies with different value, which could also be affected by the ratio of long and short sides of the hole. Importantly, we discuss the influence of relatively permittivity and permeability tensor as to the resonant modes.
In this paper, the nonlinear perfect electric conductor (PEC) inverse scattering problem was addressed with a linear model. First, finite difference frequency domain (FDFD) was used to discretize the problem. Then, the contrast and the total field were included into the contrast source to formulate a linear model. Due to the fact that the induced current only exists on the surface of the PEC scatterers,...
An arbitrarily directed and polarized plane electromagnetic wave is incident on a metallic structure consisting of a cylindrically-capped wedge perpendicularly truncated by an infinite plane. The total field is determined exactly, in the phasor domain. Particular attention is devoted to the surface currents on the structure.
In this paper, we extend the use of conventional Direct sampling method (DSM) which is only applicable to the multistatic measurement data, to the monostatic measurement data for radar imaging applications. We define a novel testing function which can be used in the indicator function of DSM with monostatic data. Numerical examples demonstrate the feasibility of the proposed method.
An Alphabet Compressive Sensing (CS) approach is proposed in this paper for the retrieval of arbitrarily-shaped targets when no a-priori information on the class of scatterers at hand is available. The approach is based on the combination of (i) a fast CS retrieval methodology that is employed to invert the field data assuming several different candidate expansion bases (i.e., the alphabet), and (ii)...
This contribution presents a new technique for constructing time-domain models from finite-element based simulation data in the frequency-domain, including frequency-dependent materials of Debye type. In order to reduce computational costs, projection-based model-order reduction techniques are applied. Not only do they provide an accurate input/output description of the system but also allow for reconstructing...
We apply high-quality discretizations to simulate electromagnetic microwaves. Instead of the vector field presentations, we focus on differential forms and discretize the model in the spatial domain using the discrete exterior calculus. At the discrete level, both the Hodge operators and the time discretization are optimized for time-harmonic simulations. Non-uniform spatial and temporal discretization...
A three-dimensional microwave imaging inversion algorithm is proposed in this paper. The developed approach is based on an efficient procedure, performing a regularization in the framework of the Lp functional Banach spaces. In order to increase the computational efficiency of the method, two specific speed-up strategies have been developed. The performances of the method have been preliminarily assessed...
The theorem for existence and for the main features of the T1(L,n) numbers (finite real positive numbers, near of kin to the positive zeros Oη,nL in the independent variable ρ of the generalized in the Thompson and Barnett's sense real regular Coulomb wave function FL(η,ρ) with ρ, η and L - all real, ρ > 0, −∞ < η < +∞ and L - finite, and n = 1,2,3…), is formulated by means of three lemmas...
A dual-frequency reconfigurable sensing antenna is proposed for temperature monitoring. A double-patch antenna with two slots is designed for dual-frequency matching with a RFID chip at Ultra High Frequency (UHF) band. Thermal switches are added to the two slots to reconfigure the resonant frequencies according to the surrounding temperature. The proposed antenna exhibits a high sensitivity, a compact...
We present results of our investigation on the use of Fourier iteration techniques to determine the antenna boresight far field from limited Fresnel region measurements in one or two planes. Measurements on two planes are well-suited to antennas not characterized by planes, such as those enclosed by radomes. Fourier iteration between two near field measurement planes also has the potential to remove...
We investigate the modal characteristics of coupled waveguides in which the supported eigenmodes coalesce; the condition we refer to as an exceptional point of degeneracy (EPD). In particular, we study different orders of EPD that can be manifested in coupled waveguides, and demonstrate how to realize a second, third, and fourth order degeneracies in the dispersion diagram of the supported eigenmodes...
The main goal of this paper is to explain the definition of the term Time-Reversal in Electrical engineering in general, and in electromagnetics for wireless communications to be specific. First, the goal will be to illustrate its claimed capabilities. Some problems with the application of time reversal in electromagnetics will be discussed both theoretically and practically. All of the time reversal...
In this work we attempt to overcome the two main limitations of the generic inverse scattering problem: the size and the ill-posed nature of the problem. We use a solver that is based on the discrete Gaussian beam summation method and apply it for the special case of a smoothly varying inhomogeneous medium. In order to overcome the need to perform simplifying approximations for the propagating medium,...
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