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Approximate Electromagnetic Cloaking of Spherical Bodies Using Nonlinear Transformation with Improved Total Scattering
Hany M. Zamel,
Essam El Diwany,
Hadia El Hennawy
Issue:
Volume 1, Issue 2, September 2013
Pages:
16-29
Received:
3 August 2013
Published:
30 August 2013
Abstract: Cloaking refers to hiding a body from detection by surrounding it with a coating consisting of an unusual anisotropic nonhomogeneous material. The permittivity and permeability of such a cloak are determined by the coordinate transformation of compressing a hidden body into a point or a line. In this work, the scattering properties of cloaked spherical bodies (conducting and dielectric) are investigated using a combination of approximate cloaking, where the conducting sphere is transformed into a small sphere rather than to a point, and using two types of nonlinear transformations; concave-up and concave-down. The radially-dependent spherical cloaking shell is approximately discretized into many homogeneous anisotropic layers, provided that the thickness of each layer is much less than the wavelength, and this discretization raises the level of scattering as the number of layers decreases. Each anisotropic layer can be replaced by a pair of equivalent isotropic sub-layers, where the effective medium approximation is used to find the parameters of these two equivalent sub-layers. The effect of nonlinearity in the coordinate transformation on the scattering performance is studied. The back-scattering normalized radar cross section, the scattering pattern are studied and the total scattering cross section against the frequency for different number of layers and transformed radius.
Abstract: Cloaking refers to hiding a body from detection by surrounding it with a coating consisting of an unusual anisotropic nonhomogeneous material. The permittivity and permeability of such a cloak are determined by the coordinate transformation of compressing a hidden body into a point or a line. In this work, the scattering properties of cloaked spher...
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The Behavior of MFIE and EFIE at Interior Resonances and Its Impact in MOT Late Time Stability
Lianrong Hong,
Guiyu Tian,
Jinpeng Fang,
Gaobiao Xiao
Issue:
Volume 1, Issue 2, September 2013
Pages:
30-37
Received:
7 August 2013
Published:
30 August 2013
Abstract: In the vicinity of a certain interior frequency, the current density on the surface of a perfect electric conducting scatterer, when illuminated by an incident field, is divided into two parts: an induced surface current caused by the incident field and a resonance surface current associated with the interior resonance mode. Equivalent RLC circuit models are proposed respectively for PEC scatterers associated with the electric field integral equation (EFIE) and the magnetic field integral equation (MFIE). Using the circuit models, together with the power conservation law, the different behavior of the resonance surface currents associated with EFIE and MFIE is analyzed and checked with numerical examples in two-dimensional space. It is shown that the interior resonance behavior has significant influence on the late time stability associated with time domain EFIE and MFIE.
Abstract: In the vicinity of a certain interior frequency, the current density on the surface of a perfect electric conducting scatterer, when illuminated by an incident field, is divided into two parts: an induced surface current caused by the incident field and a resonance surface current associated with the interior resonance mode. Equivalent RLC circuit ...
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Simulation of the S-Band Photon Vorticity Modulation Scheme
Abhay SA,
Pavaneeswar BR,
Gopinath S,
Sriram BS,
Thomas SJ,
Shanmugha Sundaram GA
Issue:
Volume 1, Issue 2, September 2013
Pages:
38-43
Received:
30 July 2013
Published:
10 September 2013
Abstract: Electromagnetic (EM) vorticity modulation is a multi-carrier scheme that offers an enhanced spectral efficiency among the several conventional communication technologies. A mathematical model of the beam-front, carrying different orbital angular momentum (OAM) states, in the S-Band region of the radio frequency (RF) spectrum has been presented using the Laguerre-Gaussian (LG) beam, to describe the effect of RF vorticity and OAM modulation. Results from EM simulations are used to verify the orthogonality of OAM states and thereby highlighting its application in a multi-user environment. Two designs of antenna reflectors are being proposed to generate the orthogonal OAM states (l=1 and 2). The existence of the OAM states is visualized from the distribution of the current densities and magnetic fields over the aperture area of the reflectors.
Abstract: Electromagnetic (EM) vorticity modulation is a multi-carrier scheme that offers an enhanced spectral efficiency among the several conventional communication technologies. A mathematical model of the beam-front, carrying different orbital angular momentum (OAM) states, in the S-Band region of the radio frequency (RF) spectrum has been presented usin...
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