摘要:

In all exact versions of scattering from a rough dielectric interface, six boundary unknowns must be found. In the Stratton-Chu equations, for example, the unknowns are the electric field (tangential and normal to the interface) and the boundary electric currents. Once determined, they are used to evaluate the three components of the scattered field and the three components of the transmitted field. The 6 x 6 operator matrix to be inverted consists of four 3 x 3 block matrices, two of which are diagonal. The other non-diagonal matrices describe the coupling. We describe a new formulation of this scattering problem in which the six boundary unknowns are the electric field and its normal derivative. In this formalism, three of the four 3 x 3 block matrices are diagonal. All the coupling resides in the fourth block.

ISSN:0920-5071    

DOI:10.1163/156939393X00480

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this paper, we discuss theoretically the effects of lossy chiral material on guided electromagnetic waves in parallel-plate waveguides. The guided-wave structures filled with chiral materials have been named chirowaveguides, and their guiding properties for lossless chiral materials have been recently studied and reported in the literature. Here, we extend the analysis of chirowaveguides to the case of lossy chiral materials, and we theoretically investigate the effect of material loss on guided modes in parallel-plate chirowaveguides. Dispersion diagrams for the real and imaginary parts of wave numbers of guided modes along with their electric and magnetic field components are given and the similarities and differences of these quantities with those of the lossless chirowaveguides are addressed. These guided-wave structures can have potential applications in the design of novel devices and components, and in electromagnetic shielding. The associated theoretical analyses for lossy chirowaveguides are steps toward further understanding of wave interaction with lossy chiral materials in wave guiding structures, and can be stepping stones towards the design of novel measurement techniques for determining material parameters of lossy chiral composites.

ISSN:0920-5071    

DOI:10.1163/156939393X00499

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The scattering of a Gaussian beam by an array of parallel circular cylinders is investigated using an iterative scattering procedure. The cylinders are made of homogeneous, isotropic dielectric material, perfectly conducting material, or a combination thereof. The iterative scattering technique is developed to evaluate both the near and far fields due to any arbitrary number of interactions between the cylinders. The technique starts with the exact series representation of the initial scattered fields from each cylinder due to the incident Gaussian beam. Then, the sum of the initial scattered fields from all cylinders is considered to be the field of an incident wave on each individual cylinder. The additional scattered field contribution is then obtained and successive scattering takes place until the boundary conditions on the surface of every cylinder are satisfied. An error criterion is developed to predict the number of iterations required to satisfy certain predetermined percentage error in the near field computations. Transverse magnetic waves (TM) are considered in detail and the extension to transverse electric waves (TE) is outlined. The effects of the incident beam parameters on the far scattered field pattern are investigated and numerical results are presented for a few examples.

ISSN:0920-5071    

DOI:10.1163/156939393X00507

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A study is done for the angular dependence of the back scattered signal power from anisotropic turbulent inhomogeneities which is described in Born approximation with the help of the power spectrum model with constant anisotropy. The aspect sensitivity obtained theoretically are compared with published data and estimations are made of the anisotropy coefficient in the low and middle atmosphere.

ISSN:0920-5071    

DOI:10.1163/156939393X00516

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A large-signal field theory of a linear version of an injection-type crossed-field amplifier is presented based on a simultaneous solution of Maxwell's equations and the equations of electron motion in the interaction region. A key step in the analysis is a representation of the field components in the interaction region as functionals of the electron-arrival time and the electron-transverse position. Substitution of this representation into the equations of electron motion, modified to allow for the interception of the beam by the slow wave structure and the sole, puts the latter into the fixed-point format for a pair of nonlinear operators in an appropriate function space. The fixed point, and hence the solution for the field components may be obtained by standard successive approximation techniques. Numerical computation of the amplifier parameters based on such a successive-approximation solution will be deferred to the second part of this contribution.

ISSN:0920-5071    

DOI:10.1163/156939393X00525

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The formulations of the extinction and scattering losses of an electromagnetic plane wave exciting a Mie sphere are well known in the literature. However the absorption loss does not have an expression of its own. In this study, an expression for the electromagnetic energy absorbed within a Mie sphere is derived directly from Ohms' law in terms of the inner field Mie coefficients. This expression is verified as the difference between the extinction and the scattering losses which are formulated in terms of the scattered field Mie coefficients. This absorbed energy expression can be used to check the accuracy of the calculated extinction and scattering losses of Mie spheres. Also, in reaching to the expression giving the difference between the extinction and scattering losses the relations between the inner and scattered field Mie coefficients are revealed.

ISSN:0920-5071    

DOI:10.1163/156939393X00534

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this paper we present modifications of the hybrid integral equations formulated in the authors' previous work for the analysis of scattering by inhomogeneous lossy dielectric/ferrite cylinders near a planar media interface. The hybrid integral equations are modified for the following two cases: an inhomogeneous cylinder of discontinuous electromagnetic parameters and a coated conducting cylinder, near the interface. Both the transverse magnetic (TM) and transverse electric (TE) excitation are considered.

ISSN:0920-5071    

DOI:10.1163/156939393X00543

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A new class of waveguides, chiroferrite filled coupled guides, (CFCL) is introduced which exhibit some novel nonreciprocal properties owing to the interaction effects between gyrotropy and chirality. These CFCL structures consist of two parallel guides coupled via a chiroferrite or ferrite-chiral composite medium. The phenomena occurring in CFCL in the presence of two propagating even and odd modes are analysed using the coupled mode method. Two nonreciprocal phenomena are observed. It is found that the polarization plane of the electromagnetic wave propagating in the structure rotates with different rotation angle and its polarization ellipticity having different values when the magnetization or propagation direction is reversed. These nonreciprocal behaviours show the feasibility of CFCL structures as a new type of nonreciprocal devices for millimeter and optical wave applications. The results of the analysis are applied to derive the scattering matrix of a section of symmetrical CFCL. The conditions indispensable for nonreciprocal operation of the structure are obtained.

ISSN:0920-5071    

DOI:10.1163/156939393X00552

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939393X00561

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939393X00570

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor