The electromagnetic scattering from a perfectly electric conducting (PEC) target located above or below rough surface is investigated, for the case of TM polarization, using the Method of Moments (MoM). The rough surface with Gaussian profile is used to emulate the realistic situation of a statistically-rough surface, while the tapered incident wave is chosen to reduce the truncation error. The Monte-Carlo procedure is employed to calculate the angular correlation function (ACF), which is dependent on the depth, size and horizontal position of the buried target, as well as the moisture content in the soil, and the properties of the rough surface. The enhancement of the ACF on the non-memory line can be used to detect a target below the rough surface. The analysis on the statistical characteristics is also carried out, in view of the study on target detection.

Earth-reflected GNSS (Global Navigation Satellite System) signals have become an attractive tool for remote sensing, e.g., ocean altimetry and scatterometric ocean wind measurements. For ice sheets, the large penetration capability and the large-scale surface averaging of the L-band signals could open a new look on firnpack characteristics like accumulation rates. In this paper we investigate theoretically reflections of GPS (Global Positioning System) signals from ice sheets. We derive a model of the reflection signal and perform simulations of airborne and spaceborne measurements. The results show that the signal, though complex, is sensitive to the roughness of the snow surface (and internal interfaces) and to firn parameters like accumulation rates. To extract valuable and concise information from the complex signal, we derive an example procedure that focusses on particular ground zones during a satellite receiver pass. The results indicate that it should be possible in principle to separately infer surface and firnpack parameters from the measurements. We conclude that GNSS reflections over ice sheets should be further persued, in particular by obtaining experimental data.

It has been analyzed physical features of the modes behavior in a waveguide filled with the chiral medium. Both mathematical and physical models of their propagation have been defined and modes classification has been suggested. It has been shown that the same root feature in dispersion is typical both for chirowaveguide modes and for the unchiral waveguide; however the mode transfiguration is peculiar to all chirowaveguide modes and this determines the complex character of the final dispersion curves behavior. The following features are typical for chirowaveguide modes: connections between polarizations and between wave types, intersections of the dispersion curves, the spatial beatings and consecutive changes of the eigen function while moving the operating point along the dispersion curve (the mode transfiguration). The chirowaveguide performs polarization selection of propagating waves in such a way that only right-polarized waves can exist under big values of propagation constant in the chirowaveguide; the mode transfiguration is the reason of this.

In this paper we describe radio wave propagation within mixed residential area consisting of vegetation and houses. We assume no specific knowledge of the houses and vegetation location,but only of their statistical parameters. A three-dimensional (3D) stochastic approach,whic h is based on the statistical description of the terrain features,houses and vegetation,and deterministic description of signal decay is presented. The scattering and diffraction from trees and buildings,as well as the diffused reflection from the rough structures of the obstructions are modeled using the statistical description of an array of non-transparent phase screens randomly distributed on the rough terrain. The model,whic h accounts for single scattering and diffraction phenomena and a similar model,whic h accounts for multiple scattering effects without effects of diffraction are compared with measurements carried out in typical rural mixed residential areas with vegetation. The accuracy of the theoretical prediction is analyzed accounting possible variations of the terrain features. The approach presented here is applicable in many cases,where specific topographical information is not available.

A simple and direct method to the problem of twodimensional electromagnetic scattering from a dielectric cylinder with multiple eccentric cylindrical inclusions is proposed. The method is based on the T-matrix approach. An aggregate T-matrix of the external cylinder for TM-wave and TE-wave excitations is derived in terms of the T-matrices of individual cylinders isolated in the host medium. The backscattering and differential scattering crosssections of the host cylinder are easily obtained by matrix calculations for the aggregate T-matrix. Numerical investigation is presented for the case where all cylinders have circular cross-sections. Numerical examples for up to three inclusions demonstrate that the scattering characteristics are significantly influenced by the internal asymmetry and inhomogeneity pertinent to the locations and material of the inclusions.

In this paper, we investigate the electromagnetic scattering by a multilayer gyrotropic bianisotropic circular cylinder in free space. The coupled wave equations of longitudinal field components in the gyrotropic bianisotropic medium are derived. The eigenfunction expansion method is used to solve the scattering problem after uncoupling the coupled wave equations. A 12 × 12 or 16 × 16 linear algebraic equation is solved for two cases: one with the center being a perfect electric conducting (PEC) cylinder; and one without the PEC center, respectively. The gyrotropic bianisotropic media can be degenerated into gyrotropic medium, uniaxial bianisotropic medium, biisotropic medium and chiral medium etc. Numerical results presented for the last case was shown to agree exactly with published results. Numerical results of electromagnetic scattering by gyrotropic bianisotropic circular cylinders are presented also.

Length reduction of evanescent-mode ridge waveguide bandpass filters is investigated extensively. Based on the conventional filter configuration, two new filter configurations are proposed: one is the generalized filter, and the other is the folded filter. In the generalized filter configuration, the cross sections of the evanescent waveguide and the ridge waveguide are not necessarily the same. It is found that the filter length can be reduced by enlarging the evanescent waveguide height. In the folded filter configuration, the filter is folded back at the middle coupling section. The folded junction is ridged to provide the required coupling between the two ridge waveguide resonators it connects. A design example demonstrates the feasibility of this filter configuration.

Starting from a continuous plane-wave representation of the electric and magnetic fields, spatial auto- and cross-correlation functions for field components and their modulus are derived in the three-dimensional Rayleigh channel case. It is shown that existing results, generally relying on two-dimensional or isotropic models, can significantly differ from those obtained thanks to a three-dimensional approach.

Full wave optimization is implemented to design a wide band transition from shielded stripline to ridge waveguide. A bandpass ridge waveguide filter, with input/output realized through tapped-in stripline is designed. Using rigorous mode matching technique the generalized scattering matrices of all the building blocks are obtained. Design procedure is described and examples are given to demonstrate the features of the tapped-in coupling structure. The tapped-in structure results in a considerable reduction of the filter's total length compared to the use of two transitions.

A forest made of an infinite biperiodic array of trees over a lossy ground, is illuminated by a linearly polarized electromagnetic plane wave in the range of 20 to 90 MHz. Due to the ratio of the wavelength to the array period, only the specular mode is propagative. Therefore, a reflection coefficient is computed and not a backscattering coefficient. It is obtained by means of a full wave approach, based on an integral representation of the electric field. This approach takes into account all possible interactions between each component of the medium as well as ground penetration and provides full information on the phase of the scattered field. Two models of the forest are developed, the two layers one where trees are separated and the four layers one whee the canopy is replaced by an equivalent homogeneous medium. The low frequency (VHF) used here make this homogenization possible and allows one to consider trees with simple shape, the wave being unable to sense details of a tree.

Theory of scattering by conducting, lossy dielectric, ferrite and/or pseudochiral cylinders is investigated using a combination of a modified iterative scattering procedure and the orthogonal expansion method. The addition theorems for vector cylindrical harmonics, which transform harmonics from one coordinate system to another, are presented. The scattered field patterns for open structures and frequency responses of the transmission coefficients in a rectangular waveguide describing the resonances of the posts on the dominant waveguide mode are derived. The validity and accuracy of the method is verified by comparing the numerical results with those given in literature.

In this study, by introducing fundamental composition principle in space and time domain, a trial of applying two stochastic evaluation methods to compound electromagnetic wave leaked from ITE group under parallel working situation are proposed. More specifically, a combined theory for the probability distribution based on the extended additive law on the cumulant statistics including an additive property for energy state quantity is proposed. Next, as a fundamental process in a time domain, an evaluation method for a compound of time ratio presenting in each state based on a stochastic exclusive property is proposed. The effectiveness of the proposed theory is experimentally confirmed by applying it to the observation data leaked from VDT group in the actual office environment.

Nowadays, electrically large complex electromagnetic problems exist in modern defence and communication industry. Accurate and efficient calculation for such electromagnetic radiation and scattering is a high computational complex task and a challenge to conventional electromagnetic solvers such as Method of Moment (MOM) where high memory and long computational time are required owing to its large size compared to operating wavelength. This paper presents the fast solution method with wavelet transform in the computation of scattering from large scale complex objects. Because of the vanishing moments, the moment matrices arising in these problems are sparsified by wavelet, and consequently, the induced current and equivalent magnetic current can be obtained quickly. Moreover, a precondition method is postulated and implemented in the fast solution of the transformed moment matrix equation with iteration methods.

A spectral-domain solution is employed to completely characterize the two-dimensional electromagnetic plane-wave scattering problem by a perfectly conducting circular cylinder buried in a dielectric half-space. Use is made of the plane-wave spectrum to consider the diffraction, reflection and transmission of cylindrical waves. Suitable adaptive integration techniques are employed to numerically solve the spectral integrals. The method is valid for any value of the cylinder radius, and of the distance between the cylinder and the interface. Numerical results are presented for both near- and far-field cases and for both TM and TE polarizations, and a comparison with other results in the literature is discussed.

For almost a century, velocity dependent scattering problems are solved in the context of Einstein's Special Relativity theory. Most interesting problems involve non-uniform motion, which is heuristically justified by assuming the validity of the "instantaneous velocity" approximation. The present study attempts to provide a consistent postulational foundation by introducing boundary conditions based on the Lorentz force formulas. The methodology used here is dubbed "reverse engineering": Being aware of the relativistic results, we show that they are replicated, (at least) to the first order in β = v/c by the present method. Specific problems are discussed to demonstrate the power of the method, and pave the way to future research in this problem area. Specifically, by realizing that at the boundary we deal with signals, which are derived from waves, only the latter being subject to the wave equations, it is feasible to apply boundary conditions and construct appropriately the scattered waves in space. It is shown that the present approach is also consistent with the Minkowski constitutive relations which are exploited for solving problems where the medium moves parallel with respect to the boundaries.

A study of the diffraction and scattering of a transverse electric X-wave by conducting bodies is presented based on the timedomain, uniform theory of diffraction method and the pulsed plane wave representation of an X-wave. The latter allows the calculation of the diffraction and scattering of each pulsed plane wave component of the incident X-wave at the observation point. The superposition of the individual diffracted and scattered pulsed plane wave components yields the diffracted and scattered field due to an incident X-wave. First, the scattering from a perfectly conducting infinite wedge is studied. Then, the case of a circular conducting disk is considered as an example of a finite scatterer. Numerical results illustrating the effectiveness of the approach, as well as an estimate of the limits of its applicability, are provided.

A parametric study is performed to the conical and Gaussian profiled horn antennas. Corrugations are added to these horns to further improve their radiation characteristics. The analyses are performed numerically using a body of revolution code, which uses the method of moments. The obtained numerical results are illustrated graphically to show the performance of the horns in terms of phase center, return loss, efficiency with parabolic reflector, directivity, and cross polarization of the horns. Results obtained conclude that the Gaussian profiled horns perform better than the existing conical horn antenna system. The Gaussian profiled horns provide higher efficiency, lower cross polarization, lower sidelobe levels as well as wider bandwidth. The objective of this article is to provide some understanding to the Gaussian profiled horns that might be of help to the new antenna designers.

Integral equation formulation and magnetic potential Green's dyadics for multilayered rectangular waveguide are presented for modeling interacting printed antenna arrays used in waveguidebased spatial power combiners. Dyadic Green's functions are obtained as a partial eigenfunction expansion in the form of a double series over the complete system of eigenfunctions of transverse Laplacian operator. In this expansion, one-dimensional characteristic Green's functions along a multilayered waveguide are derived in closed form as the solution of a Sturm-Liouville boundary value problem with appropriate boundary and continuity conditions. A method introduced here is based on the transmission matrix approach, wherein the amplitude coefficients of forward and backward traveling waves in the scattered Green's function in different dielectric layers are obtained as a product of transmission matrices of corresponding layers. Convergence of Green's function components in the source region is illustrated for a specific example of a two-layered, terminated rectangular waveguide.

Using rather general assumptions, wave beam propagation is considered in a medium constituted of two half-spaces with smoothly changing properties, these latter changing stepwise at the half-spaces' interface. Expressions for the beam-shape change in the course of propagation are obtained. General results are applied to a Gaussian beam propagating in a series chain, and to fields described by the Helmholtz equation.

An analytical boundary condition for modeling the electromagnetic properties of planar regular dense arrays of dipole particles for oblique incidence of plane waves is developed.The regular array is assumed to be dense which means that the dipole particles are close to each other.The interaction between the dipole particles is taken into account by interaction constant.The expression for the interaction constant is written in analytical form and is used for developing a transmission-line model for arrays of planar dipole scatterers.The regular dense array is modeled as a shunt impedance which is different for TM and TE polarizations.