Scattering Of EM Waves Research Articles

The Regularization Technique in Modeling of the Plane E-Polarized EM Wave Scattering by Coplanar System of Electrically Conducting Flat Strips

The integral equations technique has been successfully modified for studying the plane E-polarized electromagnetic wave scattering by multilevel coplanar systems of zero-thickness impedance strips. Reformulation of the scattering problem in the form of the second-kind regular integral equations has been realized on the base of the Carleman regularization technique. Two novel and original classes of specific Cantor functions have been presented and analyzed. Using new Cantor functions, it is easy to create a lot of non-classical orderings for specific multilevel coplanar strips systems. That sort of system can be useful for modeling irregular natural processes and zones in the future. Considerable attention was focused on the plane E-polarized electromagnetic wave scattering by sparsely filled coplanar systems of electrically narrow impedance strips. An explicit solution of the scattering problem has been obtained for such case of strips system.

Radiation and Scattering of EM Waves in Large Plasmas Around Objects in Hypersonic Flight

The hypersonic flight regime is conventionally defined for Mach > 5; in these conditions, the flying object becomes enveloped in a plasma. This plasma is densest in thin surface layers, but, in typical situations of interest, it impacts electromagnetic wave propagation in an electrically large volume. We address this problem with a hybrid approach. We employ the equivalence theorem to separate the inhomogeneous plasma region from the surrounding free space via an equivalent (Huygens) surface and the Eikonal approximation to Maxwell equations in the large inhomogeneous region for obtaining equivalent currents on the separating surface. Then, we obtain the scattered field via (exact) free-space radiation of these surface equivalent currents. The method is extensively tested against reference results and then applied to a real-life reentry vehicle with full 3-D plasma computed via computational fluid dynamic (CFD) simulations. We address both scattering [radar cross section (RCS)] from the entire vehicle and radiation from the onboard antennas. From our results, significant radio link path losses can be associated with plasma spatial variations (gradients) and collisional losses to an extent that matches well the usually perceived blackout in crossing layers in the cutoff. Furthermore, we find good agreement with existing literature concerning significant alterations of the radar response (RCS) due to the plasma envelope.

EM Wave Scattering by Random Surfaces With Different Contrast and Large Roughness Heights

EM Wave Scattering by Random Surfaces With Different Contrast and Large Roughness Heights

EM Wave Scattering by Many Small Impedance Particles and Applications to Materials Science

EM Wave Scattering by Many Small Impedance Particles and Applications to Materials Science

EM-Wave Scattering by an Axial Slot on a Circular PEC Cylinder With an Eccentrically Layered Inner Coating: A Dual-Series Solution for TE Polarization

A dual-series approach is used to formulate scattering of a TE-polarized plane wave by a circular, PEC cylinder, having a longitudinal slot and enclosing two, eccentric, cylindrical dielectric layers. The dual-series equations are analytically regularized to a matrix Fredholm equation of the second kind by use of the Abel integral-transform method. The resulting infinite set of linear algebraic equations (i.s.l.a.e.) is truncated and solved numerically. The aforementioned analytical-numerical solution intrinsically takes into consideration the correct edge behavior of the field. Furthermore, the addition theorem of cylindrical wave functions is used to match the field components on any cylindrical interface. The numerical application manifests how the structure of the inner loading of this cylindrical cavity is imprinted on backscattering. Moreover, it is shown how the location of the innermost dielectric cylinder may contribute to the suppression or enhancement of resonances.

Scattering From Axisymmetric Dielectric Scatterers: A Hybrid Method of Solving the Surface Integral Equations

Scattering of EM waves from homogeneous dielectric scatterers is formulated in terms of two surface integral equations, for the components of the total electric and magnetic fields that are tangential to the surface of the scatterer. Two equivalent systems of such equations may be used, corresponding to the two types of Maue's integral equations for perfectly conducting scatterers. The appearance of surface divergence terms of both components in the dielectric case, in addition to the unknowns themselves, causes serious complications when the method of solution is based on some kind of division of the scatterer surface into patches; these complications become particularly apparent in the process of evaluating the locally dominant self-patch contribution to the surface integrals. They can be effectively avoided if a third equivalent system of surface integral equations is used, arising from a proper summation of the original two systems; then, the two singular Green functions that appear in the surface divergence terms are replaced by their non-singular difference and this, followed by a further transformation of these critical terms, results in the complete elimination of the surface divergence terms. The self-patch contribution can then be evaluated analytically and this helps reduce the size of the matrix, via which the values of the tangential field components at the patch centers are calculated. Scatterers of considerable electrical size, for instance spheres with ka of the order of 10 or 15, can then be treated with moderate size matrices. Numerical results for spheres, sphere-cone-spheres and other shapes are obtained and compared with results from other methods. Apart from spheres, results for other shapes are very rare and limited to small sizes in the literature.

Correction to "Scattering of EM waves from a slightly rough surface of a generally anisotropic plane-layered half-space"

Correction to "Scattering of EM waves from a slightly rough surface of a generally anisotropic plane-layered half-space"

Scattering of EM waves by inhomogeneous dielectrics with the use of the method of moments and 3-D solenoidal basis functions

The solenoidal basis functions defined on tetrahedrons are modified to permit the analysis of the problem of scattering of electromagnetic waves by inhomogeneous dielectric objects. In the analysis of the scattering of EM plane waves by an inhomogeneous dielectric cube, we compare our results with those obtained using pulse basis functions. We also apply our method in the analysis of the scattering of EM plane waves by an inhomogeneous dielectric sphere, and compare the results with those obtained using the Mie's series. Finally, we apply our method in the analysis of the electromagnetic fields induced inside human tissue. We compare these results with those obtained using pulse basis functions. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 42–46, 1999.

Scattering of EM waves from a slightly rough surface of a generally anisotropic plane-layered halfspace

The problem of plane wave scattering by a slightly rough boundary of an arbitrarily layered medium with general anisotropy of electric and magnetic properties is considered using boundary conditions transference method and a small perturbation approximation combined with the Green's functions technique. It is shown that in the Born approximation, the second statistical moments of the fluctuation field scattered from an inhomogeneous anisotropic halfspace can be expressed exclusively in terms of the external parameters referring to a flat boundary and the spectral density of roughness. In the present circumstance, the set of the external parameters includes the four plane-wave reflection coefficients from a flat boundary and the (limiting) values of constitutive parameters of the adjacent media at said boundary, Within the framework of the outlined approach, the covariance dyads, Poynting's vector, scattering coefficients and Stokes parameters of the fluctuation field, and the Mueller matrix for a rough boundary are calculated.

Scattering of EM waves by homogeneous dielectrics with the use of the method of moments and 3D solenoidal basis functions

Scattering of EM waves by homogeneous dielectrics with the use of the method of moments and 3D solenoidal basis functions

Scattering of EM waves by homogeneous dielectrics with the use of the method of moments and 3D solenoidal basis functions

The use of rectangular and triangular basis functions with the method of moments to analyze the problem of scattering of electromagnetic waves by dielectric objects with high dielectric constant (ϵ r> 10) leads to convergence problems due to the spurious charges associated with the basis functions. In this article we use the method of moments and a solenoidal 3D basis function to analyze the scattering of EM waves by homogeneous dielectric objects. We present results showing the effectiveness of the formulation. © 1996 John Wiley & Sons, Inc.

Scattering cross-section of an inhomogeneous plasma cylinder

Scattering of em waves by the plasma cylinder is of significance in radar target detection, plasma diagnosis, etc. This paper discusses the general method tocalculate the scattering cross-section of em waves from a plasma cylinder which is radially inhomogeneous and infinitely long. Numerical results are also provided for several plasma density profiles. The effect of the electron density distribution on the scattering cross-section is investigated.

The Propagation and Scattering of EM Waves with TE Polarization in Electrically Large Ducts

The electromagnetic scattering from large curved ducts with complex terminations is studied here by a hybrid technique. The propagation of electromagnetic waves in the duct is analyzed in terms of an approximate modal solution. A finite-difference technique is employed for computing the reflection characteristics of the complex terminations. Numerical results are obtained for two-dimensional geometries.

The Propagation and Scattering of EM Waves with TE Polarization in Electrically Large Ducts

The Propagation and Scattering of EM Waves with TE Polarization in Electrically Large Ducts

A comparison of cloud models (EM wavescattering)

Five different cloud models are compared over a broad frequency range. They are the model of K.L. Gunn and T.W. East (1954), the model of H.J. Liebe et al. (1989), D.H. Staelin's (1966) model, S. Slobin's (1982) model, and the model of E.E. Altshuler and R. Marr (1989). A short tutorial review of the theoretical basis and limitations of each cloud model is included. It is shown that the models all tend to agree at frequencies below 40 GHz, and for light to medium cloud conditions; however, above 10 GHz and for heavy to very heavy clouds, the models diverge. >