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A new approach for obtaining metasurfaces realized by employing Frequency Selective Surfaces (FSSs) with small periodicity printed on a new class of high dielectric constant materials is presented. The synergic use of ad-hoc engineered materials and innovative electromagnetic design provides an improvement of the overall device in terms of size reduction and radiative properties.
In recent years, the computational electromagnetics community has witnessed a rapid increase in the electrical size of scattering problems that can be solved. This increase can be mainly attributed to the use of boundary integral equations and the development of the multilevel fast multipole algorithm (MLFMA) and its parallelized analogues. However, many challenges remain, especially when it comes...
Many physical materials that we wish to interrogate with electromagnetic signals are conductive. Thus, we need to understand the propagation dynamics of electromagnetic pulses through dispersive, conductive materials. Closed-form solutions are preferable to numerical solutions in that they provide an explicit expression for the dependence of the propagated field on the physical parameters. Here, we...
The retrieval of people trapped in buildings in fire or partially destroyed is a priority for rescue teams. Given the widespread use of mobile phones by the general public, an innovative idea to retrieve victims or to track rescue teams consists in capturing, via an antenna array acting as subrogated base station, the signals transmitted by cell phones (even if these are in idle mode). Real-time postprocessing...
We are investigating the feasibility of single-walled carbon nanotubes (SWCNTs) as contrast agents for microwave breast cancer detection. We hypothesize that the accumulation of SWCNTs in a tumor will enhance the dielectric contrast between normal and malignant tissue and potentially improve the efficacy of microwave imaging techniques. As an initial step, we constructed tissue-mimicking phantom materials...
In order to characterize channel dynamics accurately, antennae with high gain and high efficiency is required. This is the reason why in this work we propose the design of a high-gain antenna array with beamforming capabilities.
In this paper, the authors investigate the use of carbon-fiber composite material for the radiating element for an radiofrequency identification antenna, the T-match folded bow-tie antenna. We consider two kinds of composites that have relatively high electrical conductivity for the radiating element: (1) a braided tissue of carbon fibers embedded in epoxy resin, and (2) reinforced long carbon-fibers...
The possibility to realize artificial magnetic conductors using grounded uniaxial materials has been investigated. The results have been verified with numerical simulations for the TM polarization.
Enormous efforts have been devoted in developing principles, designs, and numerical validation schemes for transformation medium devices in various physical fields. This article reviews recent studies in the area of transformation optics applications. These studies include proof-of-concept numerical simulations of cloaking, near-to-far field magnified imaging and light-concentrating devices built...
This paper proposes and experimentally verifies a novel in-situ and broadband probe for material characterization including both the complex permittivity and permeability measurements. The probe design is based on using two sections of multi-conductor TEM transmission line and unique post processing algorithm for the determination of both epsiv* and mu* from S-parameters measurements.
A practical design guidance of a wide band shielded GPR antenna is discussed. The designed antenna is used in a GPR system working at 400 MHz center frequency. Measured data show that with properly designed shielding and absorbing materials, the bow-tie antenna with shield performs as desired. Besides antenna design, the key issues in a shielded GPR antenna design are the depth of the shield box and...
In this paper we use a coordinate transformation to create a cloak that covers a triangular-shaped conducting object placed on a ground plane. A finite-difference time-domain (FDTD) algorithm that uses non-orthogonal mesh cells (NFDTD) is initially utilized to test the full cloak. Using the coordinate transformation method, we have designed a ground-plane cloak that is an approximate version of the...
The far-field radiation of a Hertzian dipole for a two-layered gyromagnetic medium has been investigated using the dyadic Green's function. For this purpose, the symmetric property of DGFs has been employed to calculate the dyadic Green's function when an impulse source is placed above the gyromagnetic slab. After obtaining the far-field approximated DGFs, radiation fields are found for a dipole antenna...
We have clarified that the dissipation loss in artificial dielectrics is divided into two components, and how they depend on the dimensions and alignment of metal strips, and the signal frequency. One of the results has been applied experimentally to reduce the dissipation loss. Though it is a preliminary result, improvement has been appreciate the support of Research Center for 3.1 qualitatively...
A fast modeling of the wave propagation inside a rectangular room surrounded by walls of arbitrary thickness was presented. The solution was based on derivation and evaluation of the Green's function for the separable rectangular room, obtained by separation of variables method. The results for the test cases showed a good agreement when compared with the results obtained by the ray tracing technique.
This paper presents general closed-form expressions that allow to complement the Abbe sine condition formulation that is used for double material lens design, with additional important information about the maximum feed off-set position at the lens planar base and about the maximum scanning angle. This convenient information is absent from the Abbe formulation.. These expressions were tested for different...
The tool has been tested on several scenes with increasing complexity and the corresponding computational cost has been evaluated, confirming the expected speed and accuracy. The extensive testing has also shown that a deeper optimization of the code can further increase its performances. Improvements are expected by compressing the Beam Output File. While changes to the geometry data structure and...
In this paper, we introduce a new AMC structure which is implemented using an ideal homogenous material of constant permittivity and constant permeability, and we derive rigorous equations and analyze this structure theoretically. A dipole antenna on the AMC is designed and some notable characteristics are presented.
In this paper, a case of a simple antenna represented by a spherical dipole, coated by dual layers of homogeneous material, is considered and solved analytically using the spherical harmonics. The excitation is assumed to be due to a constant gap voltage. It is shown that in the works of Shafai and Kehn (2008, 2009), the classical boundary value problem solution results in unrealistic power radiations,...
In this paper, a complex electromagnetic model for the SFRC is derived, and a mathematical model for the obtention of the effective relative permittivity is described. A static analysis setup is presented and results of a two weeks duration analysis are analyzed. Finally, some preliminary conclusions for the time-dependence behaviour of SFRC are formulated.
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