The Sommerfeld integrals for the electromagnetic field due to a delta-function current in a horizontal electric dipole located on the planar boundary between air and a homogeneous dielectric are examined in detail. Similar to the case of the vertical dipole, the tangential electric fields consist of a delta-function pulse travelling in the air with the velocity c, the oppositely directed delta-function pulse travelling in the dielectric with the velocity c/ε^1/2 for the component E_ρ and the velocity cε^1/2 for the component E_φ, and the final static electric fields due to the charge left on the dipole. The appearance of the vertical magnetic field is similar to that of the tangential electric field. It is pointed out that the amplitude of the pulsed field along the boundary is 1/&rho², which is characteristic of the surface-wave or lateral pulse.

Scattering characteristic of target in rain is studied in this paper, which calculates scattering matrix of rain area and that of cylinder target in rain, taking the effect from rain into account by substituting rain media for random media with equivalent complex permittivity. SCR (ratio of scattering signal induced by target in rain to clutter from rain) is computed, and the relation between SCR and polarization status of transmitting and receiving antennas is deduced. By optimizing the SCR, optimal polarization status of transmitting and receiving antennas are found. And, the results found in this paper are serviceable for communication system design [2, 4].

In this paper, a novel reconfigurable two-layer microstrip antenna fed using a coplanar waveguide through a slot/loop combination is investigated. The slot/loop combination allows for easy reconfigurability of the frequency band of operation by incorporating switches in the feed network. Furthermore, broad impedance bandwidths were obtained by using two substrate layers consisting of a high-ε_r substrate that contains the feed network and a low-ε_r substrate that contains two patches, one patch on either side of the substrate. The two substrates are not separated by a ground plane. Impedance bandwidths of about 23% were obtained for two selectable frequency bands using two switches. The two frequency bands obtained for the parameters chosen in this paper are 8.73-10.95 GHz and 7.68-9.73 GHz.

The Electromagnetic (EM) fields of a concentric, mismatched-material, elliptical system are studied when excited by an interior or exterior electric surface current. The interior or exterior surface current is assumed to be proportional to a single, angular Mathieu mode. It is shown that despite the fact that the system is concentric, that a single Mathieu mode surface current excites EM Mathieu-mode fields of all orders. A derivation of the EM fields due a single mode electric surface in an infinite, homogeneous media is given, as well as the matrix formulation from which the EM fields of the mismatched-material, elliptical system may be determined. Validation of numerical results and comparison with other research work is given for both interior and exterior single-mode, current sources. Detailed numerical examples of the EM fields that result for a single-mode, exterior source excitation are given for the first time. Discussion of the EM mode coupling that results by single-mode excitation on a mismatched elliptical system is given.

A single-level compression algorithm is described for the plane wave response matrix, which defines the current excited on the surface of a scatterer by a spectrum of incident plane waves. The reported method is based on the physical principle that it is often possible to organize plane waves originating from a given angular region to form incident beams which excite localized currents on the surface of an electrically large target. The properties of the method are illustrated for several scattering problems in two dimensions.

The application of polarization diversity reception at the mobile terminal in micro cells at 2 GHz is presented in this paper. Ray-tracing tool is used to study effects of electric field polarization on the received power in outdoor environments. The performance of diversity schemes with vertical/horizontal polarization and +45°/−45° slanted polarization are compared in different line-of-sight (LOS) and nonline- of-sight (NLOS) environments. Based on the evaluation of cross polarization discrimination (XPD) parameters, it is clarified that different environments will affect XPD values in micro cells. Then, the vertical/horizontal polarization diversity and +45°/−45° slanted polarization diversity are chosen to compare with space diversity. Several different combining techniques of polarization and space diversity schemes are also compared in different environments. It is found that dual-polarized antennas for mobile terminal are a promising alternative for two spaced antennas.

The problem of studying modal characteristics of metallic waveguides filled with lossless inhomogeneous and/or anisotropic media, is one of studying properties of the propagation constant of the guiding structure. It is shown that modal behavior in the neighborhood of critical frequencies such as cutoff frequencies and frequencies marking the onset of complex wave mode intervals, can be modeled through approximation of the propagation constant by a root of an algebraic equation. The particular form of the algebraic function approximating the propagation constant is discussed in the neighborhood of a singularity. A numerical example is included to stress the viability of the technique.

The photon, that is the messenger of the electromagnetic force, is considered with a zero restmass. Yet, just as there is no energy with a zero value, so we talk about a "Zero Point Energy", for the equivalence between mass and energy (datum point of the Theory of Relativity and foundation of modern Physics), there should exist also a "Zero Point Mass". That is, no particle, with energy, though extremely small, as the energy of the quantum of light, the Planck's grain, can have a zero mass. In other words, just for the equivalence Mass-Energy (E = mc²), to any particle with energy should correspond a mass equal to the energy carried, divided the square of the speed of light. Of course when we consider particles like the photon this value will be extremely small, however it should be ≠ 0. Thus, a lot of the behaviours of the photon, in which it shows a clear sort of mechanic action (see photoelectric effect, Compton effect, or the Raman effect), so far ascribed to a mere energetic effect, may probably be considered as real "mass effects".

Three mathematical models based on approximate surface integral equations for electromagnetic analysis of scalar wave scattering from thin extended target are considered. Such models include different systems of the second kind singular integral equations determined on the target median. The effective algorithm for direct (without preliminary regularization) numerical solution of the systems is based on the special quadrature formulae for singular integrals. Verification of the mathematical models and their comparison is performed in the case of penetrable cylindrical shell in homogeneous non-magnetic medium.

The multilevel fast multipole algorithm (MLFMA) is used in computing acoustic and electromagnetic fields with integral equation The multilevel fast multipole algorithm (MLFMA) is used in computing acoustic and electromagnetic fields with integral equation methods. The traditional MLFMA, however, suffers from a low-frequency breakdown that effectively limits the minimum division cube side length to approximately one wavelength. To overcome this low-frequency breakdown and get a broadband MLFMA, we propose an efficient and relatively straightforward implementation of the field translations based on the spectral representation of the Green's function. As an alternative we also consider the so called uniform MLFMA, which has a lower computational cost but limited accuracy. We consider the essential implementation details and finally provide numerical examples to demonstrate the error controllability of the translations.

In this paper, two new interconnect structures called Multi-Segmented S-G-S (Signal-Ground-Signal) and S-O-S (Signal- Open-Signal) interconnects are proposed and compared with the conventional S-S-S interconnects. In these interconnect structures a multi-segmented grounded or opened line is inserted between two adjacent signal lines. The grounded (opened) lines have been grounded (opened) not only in their terminals, but also in some places along their length. The performances of these interconnects are studied via some examples.

A surface with periodic corrugations of sufficiently small periodicity is shown to be electromagnetically equivalent to an inhomogeneous transition region (slab). Explicit expressions for the inhomogeneous transition region are found for one-dimensional corrugations and for two-dimensional corrugations a local elliptic problem has to be solved in order to find the equivalent electromagnetic properties. The homogenized surface can be characterized by its surface impedance dyadic or its reflection dyadic. A few numerical examples illustrate the theory.

Differential-form formalism has been often applied, in stead of the more commonplace Gibbsian vector calculus, to express the basic electromagnetic equations in simple and elegant form. However, representing higher-order equations has met with unexpected difficulties, in particular, when dealing with general linear electromagnetic media. In the present study, wave equations involving scalar operators of the fourth order are derived for the electromagnetic two-form and the potential one-form, for the general linear bi-anisotropic medium. This generalizes previous coordinate- free approaches valid for certain special classes of media. The analysis is based on some multivector and dyadic identities derived in the Appendix.

A rigorous solution to the Neumann boundary value problem (BVP) for semicircular trough in a perfectly electrically conducting (PEC) ground plane is presented. The known Rayleigh's method expansion of a solution by eigensolutions of the Helmholtz equation in cylindrical coordinates coupled with partial orthogonality of trigonometric functions is used. In contrast to previous works on this theme, a Fredholm 2nd kind matrix equation for modal coefficients is obtained, which permits one to derive very fast convergent approximate solution for any incidence angle and trough dimension. The method solution permits one to consider a dielectric loading as well. A strong broadband fall-off of backscattering from apertures loaded with lossy dielectric is theoretically revealed.

This paper presents an innovative inverse scattering approach based on a fuzzy-logic strategy aimed at fully exploiting the information content of the scattered data in a microwave imaging system. The effectiveness of the proposed method is assessed through the results of a numerical analysis concerned with the reconstruction of single as well as multiple dielectric targets in various noisy environments. For comparison purposes, the obtained performance are compared with those of a standard method in terms of reconstruction accuracy and computational load to point out the improvement induced by the proposed approach.

Scattering by pulsating objects is discussed. In the case of the pulsating cylinder, its surface vibrates time-harmonically in the radial direction. The formalism is based on first-order v/c relativistic approximations, and on the assumption that the ambient media are not affected by the mechanical motion of the interface. This is conducive to simpler and amenable approximations. The cases analyzed display the modulation effect due to the mechanical motion at frequency Ω, creating new spectral components in the scattered wave, peaking at the sideband frequencies ω_ex ± nΩ around the excitation frequency. To put such phenomena in a quasi-relativistic and electromagnetic context, and account for the boundary-condition problem and the representation of the scattered wave is the subject of the present investigation. Such effects can be used to remotely sense the properties of the scatterer, especially its motion.

The present paper concerns the design, numerical analysis, and measurement for simple metal-plate lens structures. The power of electromagnetic waves can be concentrated by arranging flat strips parallel to one another and adjusting the transverse and longitudinal length of the waveguide regions. The simple designing procedures are described for the lenses with plane, concave, and convex profiles. These steps are practically applied to construct the lenses for the X band. In order to discuss the dependence of focusing properties on the lens and source types, we numerically analyze the scattering problems using the integral equations combined with the moment method. The lenses are made up by aluminum plates, and the field amplitude in the transmission region is measured. We confirm the formation of the focus near the design point.

In this paper, the electromagnetic field in air from a radiating horizontal electric dipole located in the homogeneous isotropic spherical electrically earth coated with N-layered dielectrics is investigated anew. The starting point is based on the formulas for the electromagnetic fields in air from vertical electric and magnetic dipoles situated in air above the surface of the earth coated with N-layered dielectrics. The complete explicit formulas are derived for the electromagnetic fields in the earth due to vertical electric and magnetic dipoles located in air. By using reciprocity theorem, the formulas are readily obtained for the six components of the electromagnetic field in air radiated by a horizontal electric dipole located in the earth.

From a very roughly random surface the backscattering enhancement is predicted due to the constructive interference of multiple surfaces scattering. For specialized surfaces involving roughness large compared with the incident wavelength, the backscattering enhancement takes place. The phenomenon of backscatter enhancement becomes evident for both larger normalized surface height and surface rms slope. In this paper we take further study to predict the backscattering enhancement mainly comes from upward multiple scattering. On the contrary the downward multiple scattering has no contributions to the scatter strength of backscattering enhancement. The model developed in this paper is based upon the integral equation method and able to predict this phenomenon of multiple scattering and backscattering enhancement. The depolarized multiple scattering makes much contribution along the plane of incidence from random rough surfaces, but depolarized single scattering makes little contributions. The total multiple scattering strength is the summation of upward and downward multiple scattering strength. In comparison of model prediction of total multiple scattering strength with measured data along the specular plane, excellent agreement is obtained.