In this paper, the Matrix-Pencil method is used to retrieve the radiation pattern of several antennas measured in different semianechoic scenarios using low directive probes, where the existence of reflected contributions can severely disturb the measurement. Starting from data measured in the frequency domain, this method allows the direct path to be identified and the radiation pattern of the antenna to be retrieved with good accuracy in all the cases under study.

In this paper, models of metallic absorbers for electromagnetic waves in the infrared to microwave frequency range are reported and discussed. The Hadley's formalism (1D model) of transmission, reflection and absorption for semi-infinite layers, which allows to design all configurations of unstructured absorber films and dielectrics is generalized. To make the micro-fabrication of the metallic absorbers easier (that means to have layers thick enough), the metallic layers need to be structured (grid for example). We developed a model that allows us to consider the structure of metal as a homogeneous layer, where the diffraction is negligible. This new layer can be used with the previous model. When diffraction effects must be taken into account, we modified an electrical model made by Ulrich. We further developed it for the configuration of a dielectric before the metallic grid. The results showed the importance to take into account all the dimensions of the grid, the dielectric layer parameters and the wavelength to design the best absorber.

We investigate the dispersion properties of both TE and TM surface polariton modes formed at the surfaces of a bilayer composed of a single-negative materials. The dispersion curves of surface polaritons modes is found to consist of two branches, and it is shown that TE and TM surface polaritons may have a simultaneous mode. The characteristics of TE and TM surface polaritons modes (the frequency, localization position, ...) are shown to depend on the relative thicknesses of two single-negative layers of the bilayer. We find that the TE and TM surface polariton modes propagate in the same directions along the interfaces of the bilayer in the most cases. Nevertheless, the TE and TM surface polariton modes may have opposite directions of propagation for appropriate thicknesses of two single-negative layers. This can be interesting especially in the case of simultaneous TE and TM surface polariton mode, for which the structure acts as a polarizing beam splitter.

In this paper, a low-cost multiband printed-circuit-board (PCB) antenna that employs Koch fractal geometry and tunability is demonstrated. The antenna is fabricated on a 1.6 mm-thick FR4-epoxy substrate with dimensions 4 cm × 4.5 cm, is microstrip-line fed and has a partial ground plane flushed with the feed line. The proposed antenna is simulated using the Finite-Element Method for three different switching cases and the return loss is measured for each case. It is shown that the antenna can cover the bands of several applications including 3G, WiFi, WiMAX as well as a portion of the UWB range. The radiation patterns are satisfactorily omnidirectional across the antenna's operation bands.

Thin dielectric sheet (TDS) approximation and electromagnetic (EM) boundary conditions are considered together to derive out a set of integral equations as an alternative to the impedance boundary condition (IBC) method to solve the electromagnetic scattering from thin dielectric-coated conductors. Only with discretizing the induce current on the conductor surfaces and solving an integral equation similar to that for a PEC, the scattering fields from the whole coating system (electric or magnetic material coating) are computed. Both the electric field integral equation (EFIE), magnetic field integral equation (MFIE) and their combination form are presented. These equations are converted to a matrix equation by Galerkin's method and then solved with multilevel fast multipole algorithm (MLFMA) to obtain the far fields scattering from these coated objects.

In this work, a Quasi Monte Carlo (QMC) Integration Technique using Halton Sequence is proposed for the Electric Field Integral Equation (EFIE) in the Method of Moments (MoM) solution for scattering problems. It is found that the Halton Sequence used in QMC integration scheme is capable of handling the singularity issue in the EFIE automatically and at the same time provides solution to the scattering problems very easily. Finally the proposed technique is applied to solve the scattering problem from a finite cylinder employing the entire domain basis function expansions. The results obtained show a good agreement between the proposed and conventional technique.

In this work we theoretically study the optical properties of a multilayer Fabry-Perot narrow band transmission filter containing a metamaterial negative-index defect. As in the usual Fabry-Perot filter design, the negative-index defect is sandwiched by two quarter-wave dielectric mirrors. Some useful design rules on selecting value of the negative-index of the defect have been numerically elucidated. Such narrow band transmission filtering is achieved when the refractive index of defect is either a negative even integer if the thickness is taken as a quarter of design wavelength; or a negative odd integer if the thickness is taken as a half of design wavelength.

The purpose of this paper is to explain an exact derivation of apparent power in n-sinusoidal operation founded on electromagnetic theory, until now unexplained by simple mathematical models. The aim is to explore a new tool for a rigorous mathematical and physical analysis of power equation from the Poynting Vector (PV) concept. A powerful mathematical structure is necessary and Geometric Algebra offers such a characteristic. In this sense, PV has been reformulated from a Multivectorial Euclidean Vector Space structure (CG_n-R³) to obtain a Generalized Poynting Multivector (S). Consequently, from S, a suitable multivectorial form (P and D) of the Poynting Vector corresponds to each component of apparent power. In particular, this framework is essential for the clarification of the connection between a Complementary Poynting Multivector (D) and the power contribution due to cross-frequency products. A simple application example is presented as an illustration of the proposed power multivector analysis.

In electromagnetic tomography and resistivity survey a linearized model approximation is often used, in the context of regularized regression, to image the conductivity distribution in a domain of interest. Due to the error introduced by the simplified model, quantitative image reconstruction becomes challenging unless the conductivity is sufficiently close to a constant. We derive a closed form expression of the linearization error in electrical impedance tomography based on the complete electrode model. The error term is expressed in an integral form involving the gradient of the perturbed electric potential and renders itself readily available for analytical or numerical computation. For real isotropic conductivity changes with piecewise uniform characteristic functions the perturbed potential field can be shown to satisfy Poisson's equation with Robin boundary conditions and interior point sources positioned at the interfaces of the inhomogeneities. Simulation experiments using a finite element method have been performed to validate these results.

A Heterodyne six-port FMCW collision avoidance radar sensor configuration based on beat signal phase slope techniques is presented in this paper. Digital IF circuitry has been used in order to avoid problems related to DC offset and amplitude and phase imbalance. Simulations show that the velocity and range to the target is obtained simultaneously, with very good accuracy. Results are compared to other techniques and system architectures.

Based on vector electromagnetic theory and the Waveguide Model, the vector Hopkins model is deduced. The model contains the vector Hopkins formula and the resist profile model of fast Optical Proximity Correction. The vector Hopkins formula considers incidence angles and azimuth angles of off-axis illumination, which differs from the traditional scalar Hopkins formula. The resist profile model is employed to analyze the effect of the photoresist diffusion under off-axis illumination by using self-adaptive Gaussian filter with scale adjustable, and a new transmission cross coefficient is obtained. The projection system parameters are introduced simultaneously, such as incidence angles, azimuth angles of off-axis illumination and diffusion parameters of photoresist. By simulating the aerial image of 3D mask in the actual lithography process, the optimal angular range of oblique incidence is studied; the image quality by impact with the oblique incidence angle is discussed as well.

In this paper, a novel version of the transverse wave approach (TWA) based on two-dimensional non-uniform fast Fourier mode transform (2D-NUFFMT) is presented and developed for full-wave analysis of RF integrated circuits (RFICs). An adaptive mesh refinement is applied in this advanced TWA process and CPU computation time is evaluated throughout 30 GHz patch antenna, application belonging to wireless systems. The TWA in its novel version is favorably compared with the conventional one in presence of AMT technique in the context of EM simulations. Another version of TWA is outlined to illustrate a computationally efficient way to handle an arbitrary mesh for RFICs analysis with high complexity problems.

In this paper, we reported an E-plane horn antenna incorporating a metamaterial. Such a metamaterial is made up of metallic cylinders organized in a two-dimensional square lattice. After properly designing the lattice constant and unit cell pattern, we synthesized a medium with the effective refractive index smaller than unity. Therefore, once the waves were excited within the metamaterial, the refractive waves tend to be perpendicular to the interface between the metamaterial and uniform medium. Based on this concept, a 4-way beam splitter was designed to equally distribute the input power into 4 different directions. We then guide each of the power into individual E-plane flared opening to radiate a directional beam pattern in each sector. We have fabricated this antenna and measured its radiation characteristics including the return loss and far-field pattern. The excellent agreement between the measured and simulated results was obtained. Due to the properties of robust, low-loss, and low-cost, this antenna may have promising application in a point-to-multiple-point downlink system.

A new approach to design digitally tunable optical filter system by using semiconductor optical amplifiers (SOAs) and Dense Wavelength Division Multiplexed (D.W.D.M.) thin film filter based wavelength selection elements is presented. The system designed with this approach is very easy to configure and expand, smaller in size, lesser in weight, cheaper in cost and consuming less power as compared to design suggested by other researchers recently.

The scattering cross section of a meta-sphere is determined and comparison is made to a normal right-handed spherical dielectric scatterer. A meta-sphere is a term used for a sphere embedded inside a medium that gives effective doubly-negative permittivity and permeability. It is found that the scattering resonances can be manipulated via the meta-sphere parameters while the issue of reducing the scattering cross section to zero is examined.

Modifying the rate equations of an injection-locked semiconductor laser, we have analyzed its optical bistability with the effect of frequency chirping of injected light. Comparison between the bistable steady-state characteristics of the laser in two cases: with and without frequency chirping is done by studying the effect of parameters such as frequency detuning, carrier injection rate, and cavity length. Then we have made a comparison between the bistable dynamic characteristics of the laser for these two cases. The results of the analysis show that the effect of frequency chirping on the bistability behavior is negligible.

An equilateral triangular microstrip antenna is proposed for circularly-polarized synthetic aperture radar (CP-SAR) systems operated in L-Band (1.27 GHz). For airborne application, a prototype antenna patch is designed, fabricated and tested. Electromagneticallycoupled, dual-feeding method is applied to generate the circularly-polarized wave radiating from the patch. The fabricated patch exhibits an axial ratio bandwidth (< 3 dB) of about 0.58% (7.4 MHz), which is consistent with the value of 0.57% (7.24 MHz) from the simulation.

Linear and circular arrays are optimized using the particle swarm optimization (PSO) method. Also, arrays of isotropic and cylindrical dipole elements are considered. The parameters of isotropic arrays are elements excitation amplitude, excitation phase and locations, while for dipole array the optimized parameters are elements excitation amplitude, excitation phase, location, and length. PSO is a high-performance stochastic evolutionary algorithm used to solve N-dimensional problems. The method of PSO is used to determine a set of parameters of antenna elements that provide the goal radiation pattern. The effectiveness of PSO for the design of antenna arrays is shown by means of numerical results. Comparison with other methods is made whenever possible. The results reveal that design of antenna arrays using the PSO method provides considerable enhancements compared with the uniform array and the synthesis obtained from other optimization techniques.

An E-wave excites longitudinal conductivity currents in a waveguide filled with lossy medium. Total flow of this current through a cross-section is nonzero for odd E-modes; it means that some charge is transported by the pulse along the waveguide. This phenomenon is considered in the paper using analytical approach based on mode expansion of the fields in Time Domain (known as Mode Basis Method) and using Finite Difference in Time Domain method (FDTD). Volume conductivity charges being moved by the pulse wave are determined. In order to set the problem as much physically as possible we consider diffraction of a pulse E-wave on the boundary between a hollow waveguide and a waveguide with conductive medium. Behavior of the transient fields and surface charges at the interface are also examined. It is shown that an incident pulse wave excites a surface wave at the interface that results in transversal resonance with relaxation time much greater than that of the conductive medium. Characteristics of the travelling charge pulse wave are studied based on the obtained closed-form solution.

The patch shape influence on the radar cross section (RCS) of a cylindrical microstrip antenna (CMA) is discussed. The RCS of the CMA is evaluated from a plane wave scattering problem solution to a cylindrical microstrip antenna. The method of moments is employed in the spectral domain using sub-domain basis functions. It is shown that the patch shape has a pronounced effect such that new resonance modes appear at frequencies substantially shifted towards the low-frequency end compared to a cylindrical rectangular patch.