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The characteristic mode (CM) theory has been widely recognized as a powerful tool for radiation/scattering analysis and optimization designs. As a natural extension of PEC CM theory and dielectric material CM theory, we propose a novel CM formulation for the systematic analysis of dielectric coated conducting bodies. The newly developed CM formulation bases on the EFIE-PMCHWT equation. Numerical cases...
Tracking PMCHWT-based characteristic modes (CMs) of dielectric or magnetic objects still remains a challenging task due to the presence of non-physical modes, but developing a robust tracking algorithm is essential to observe modal behavior over frequency. Thus, our efforts continue in enhancing an existing tracking algorithm which is based on eigencurrent correlation and far-zone eigenfield orthogonality...
Nowadays 3D printers are useful for the development and rapid prototyping of dielectric structures for radiation manipulation and support of antennas. This is possible since the materials used in this machines are essentially dielectric. These can be used as radiating elements (dielectric resonators), as radiation handlers (lenses) or as a supporting base for applying conductive material to radiation...
In this paper, the influence of conductivity values applied to the foetal tissues at 3, 7 and 9 months gestational age on the electric field distribution induced by a 50 Hz uniform magnetic field was explored by means of stochastic dosimetry performed by making use of polynomial chaos theory. The maximum variations of induced electric field peak can reach up to 12 % in foetal fat.
The compressive sampling matching pursuit (CoSaMP) algorithm is used for solving the electromagnetic inverse scattering problem on two-dimensional sparse domains. Since the scattering matrix, which is computed by sampling the Green function, does not satisfy the restricted isometry property, a damping parameter is added to the diagonal entries of the matrix to make the CoSaMP work. The damping factor...
This work aims at offering an overview on the scientific results stemming from a selection of three Short-Term Scientific Missions (STSMs) carried out in 2016 and funded by the COST Action TU1208 “Civil Engineering Applications of Ground Penetrating Radar.” The research activities focused on the development and use of electromagnetic modelling and inversion techniques for Ground Penetrating Radar...
Size-reduction of circular patch absorbing elements are analyzed by introducing slits, holes, and cut-out rings. Parametric variation results are presented for slit depth, hole size, and concentric rings to reduce the size of absorbing elements. ANSYS Electronics Desktop, a finite-element method (FEM) solver, was used to simulate the absorption from an array of circular patches, while analyzing parametric...
Efficient closed form solutions are proposed for computing the time domain diffraction coefficients related to plane waves impacting a structure consisting of two co-planar adjacent blocks formed by metallic and dielectric materials. They are determined by applying the inverse Laplace transform to the corresponding Uniform Asymptotic Physical Optics diffraction coefficients in the frequency domain...
In this paper, we present a complex discontinuity in stratified structure by hybrid numerical methods. A rigorous analysis of the transverse operator formulations is carried on inhomogeneous coaxial cable filled with dielectric sample for propagation constants and the corresponding normalized field distributions. The new multimodal variational method is used to describe the dispersion characterization...
An approach for microwave imaging of brain strokes is presented. Numerical simulations show the potentialities of this technique in retrieving the dielectric properties of biological tissues inside the head. An efficient iterative two-loop method is used to face the ill-posedness of the considered inverse scattering problem, which is formulated in terms of integral equations.
In this contribution the strengths and the weaknesses of microwave imaging techniques for the reconstruction of dielectric and velocity profiles of inhomogeneous cylinders in non-uniform axial motion are presented. Some numerical results are presented to support the main conclusions.
A variety of material measurement systems based on transmission/reflection line method are available to characterize the dielectric properties of materials by extracting the S-parameters using a Vector Network Analyzer (VNA). A waveguide material measurement facility based on transmission/reflection line method has been developed in-house in order to accurately deduct relative dielectric permittivity...
This paper proposes a reconfigurable frequency selective surface (FSS) operating in the X band composed of triangular elements periodically placed on a single FR-4 dielectric layer. The reconfiguration of the proposed FSS allows a quasi-linear variation of the rejecting resonant frequency as function of the incident wave angle. The variation of the incident wave angle is provided by rotation of the...
We use phase perturbation theory to design a one-dimensional randomly rough interface between two dielectric media that produces a specified mean differential transmission coefficient for light transmitted through it.
We present an approach for a fast and accurate determination of the geometrical optics solutions to Maxwell's equations based on the determination of the eikonal function and devised to handle scenarios involving complex spatially varying refraction indices. The explicit solution of the eikonal equation allows to set up an inverse ray tracing scheme, which proves particularly convenient compared to...
In this paper, a fast (and) convergent method to analyze propagation in polygonal cross-section dielectric waveguides is presented. The problem formulated as an homogeneous surface integral equation in the spectral domain is discretized by means of Galerkin method with analytically Fourier transformable expansion functions reconstructing the behavior of the fields on the wedges. Moreover, the elements...
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