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A geometrical formulation of a space-time finite integration (FI) method is studied for effcient computations of electromagnetic wave propagation. A space-time dual grid is constructed based on the Hodge duality and Lorentzian metric. A relation between the incidence matrices of space-time primal and dual grids is compared with the geometrical relation in the Euclidean space. 3D space-time Maxwell...
Tunneling of electromagnetic energy can take place in narrow (sub-wavelength) channels filled with either the epsilon-near-zero materials or resonant wires. Since the tunneling is accompanied by very intense electric fields, the resulting frequency response is highly selective. In this paper, a microstrip bend is studied that supports energy tunneling. It has been shown, through full-wave simulations,...
A multi-layer transmission cloak formed from ordinary dielectrics for hiding cylindrical objects with diameters exceeding incident wavelengths is developed. The Helmholtz equation solution and the Genetic Algorithm have been used to find the optimal dielectric constants and thicknesses of the cloak layers. Full-wave simulations have demonstrated that the designed cloak can provide efficient wave front...
This paper presents a design methodology for a dual-frequency unequal-split Bagley power divider (BPD). This is accomplished by replacing each quarter-wavelength transmission line by T-shaped transmission lines network. Simulation results obtained using the full-wave IE3D simulator prove the validity of the design procedure.
To reconstruct objects buried in layered media, most of current imaging methods are based on a common assumption that the dielectric properties of layered media are given. However, this assumption is unrealistic in practice. To study a more realistic electromagnetic inverse scattering problem in which the dielectric properties of layered media are not given, an inverse scattering series (ISS) method...
In this paper, a hybrid algorithm based on non-overlapping domain decomposition method and surface Integral equation (SIE-DDM) is presented for dealing with time-harmonic electromagnetic (EM) problems of dielectric or composite object. The proposed method divides the composite object into homogeneous, non-overlapping sub-domains. Robin transmission condition is introduced to weakly enforce the continuity...
The authors have previously proposed and experimentally verified a microwave medical sensor for monitoring vital signs including the lung water content. It is proposed that, with a careful and medically based designed array of such sensors, both surface and in-depth vital signs can be extracted accurately. For such array design, realistic human models can be used in full-wave simulators with the help...
Several approaches to reducing the blockage effects introduced by a rod- or wire-type antenna, obstructing the field of view of a reflector or another monopole, have been investigated and their performances have been compared. The far field patterns of the obstructed antenna in the presence of the blockage, with and without the cloak, have been numerically simulated.
This paper presents a compact triple band metamaterial antenna for different wireless applications. The designed antenna is based on a new configuration as half mode metamaterial left handed transmission line. The proposed antenna was designed to cover the frequency bands from 2–2.4 GHz, 5.4–6 GHz, and 6.8–8 GHz. The theoretical design principles of half mode left handed transmission line antenna...
In this work we develop a novel passive structure whose unit cell incorporates a passive electromagnetic diode and chiral metamaterial structure to break the system's symmetry and achieve Faraday-like rotation with no need for magnetic bias.
EM modeling of real life structures in the majority of cases starts from an appropriate CAD model. In order to prepare such a model for EM simulation, the model has to be meshed. A novel and efficient quadrilateral mesh technique is presented in this paper. The efficiency and accuracy of this technique is compared with two other quad meshing techniques.
This paper theoretically presents scattering characteristics of a TM electromagnetic plane wave of an electrically short period subwavelength slot grating in a thick metal plate, using mode matching technicque. The scattering characteristics are numerically calculated on the condition that the period is much shorter than a wavelength of the incident electromagnetic wave, and it is theoretically discussed...
An infinite grating of coated PEC cylinders is illuminated by a normally incident electromagnetic wave. The formulated boundary value problem is solved rigorously with the use of coordinate translation formulas and the reflected/transmitted fields are readily determined. The conditions for perfect absorption are derived and the error quantities expressing how well are these conditions fulfilled are...
The use of transformation optics concept to change the physical size of radiating sources is investigated. By choosing transformations that compress space, and then match it to the surrounding radiation environment, we are able to miniaturize the physical size of the embedded source. We show that a small aperture antenna can then behave as one with a large aperture. A study of the transformation of...
An image rule expression for the radiated fields from a spherical wave source above a perfect electric or magnetic conductor is presented. A matrix notation is introduced that simplifies further the presentation. It is shown that fields can be computed through a reflection matrix whose properties ensure satisfaction of boundary conditions. Comparisons with the fields computed by a commercial solver...
A self-structuring electromagnetic scatterer (SSES) based on a novel conductor-backed template is proposed. The SSES with an embedded search algorithm can alter its electrical shape to fulfill different scattering objectives, such as RCS reduction (RCSR) or enhancement (RCSE). Each constituent element in this conductor-backed SSES template has a larger tuning phase range so that it outperforms the...
Recently, some variations of the Biogeography Based Optimization, named MmCn-BBO have been introduced. The newly introduced features were aimed to improve the performances of the standard algorithm. In this paper the authors compare the performances of the different developed schemes, by applying them to several test functions and to real-world electromagnetic problems.
Gas discharge can be ignited in micro-scale gaps even with small voltages commonly found in many RF applications, electronic devices and miniaturized antennas. This discharge may eventually lead to gas breakdown which could result in performance degradation or even device failure. In this paper, an algorithm for the simulation of electromagnetic effects of gas discharge phenomena is presented. For...
The reverberation time has been measured in a reverberation chamber for different loads and for a cross polarized transceiver at the frequency of 1.8 GHz. We determine the whole-body absorption cross section of a canonical phantom using a maximum-likehood high-resolution channel parameters estimator - RiMAX - and good agreement has been obtained with the result from the numerical simulations. The...
We report on a novel metamaterial design based on multi-turn spiral resonators which strongly enhance nonlinear coupling between electromagnetic and mechanical response. The robust fabrication procedures allowed to produce a large number of resonators, suitable for assembling large metamaterials arrays. We experimentally demonstrate a remarkable self-tuning of the electromagnetic resonance, achieved...
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