摘要:

The standard impedance boundary condition (SIBC) does not constitute an exact model of material coated perfect conductors with edges but may provide sufficient accuracy for engineering purposes. A numerical investigation of the SIBC accuracy is carried out for coated wedges and coated square cylinders for the case of transverse magnetic (TM) illumination. The numerical investigation reveals that although the SIBC model is less accurate for structures with edges than for planar structures, it remains applicable for a wide range of engineering problems. Hence, the TM far field from a large class of coated conductors with edges can be accurately predicted using the SIBC model.

ISSN:0920-5071    

DOI:10.1163/156939398X00863

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The differential cross section of layered lossy dielectric cylinders of finite length due to a plane electromagnetic wave at oblique incidence is derived. The solution is obtained by approximating the fields within the finite-length cylinders by those which would exist in infinite-length cylinder having the same permittivity, orientation and size. The scattered field relations are then used to obtain the differential cross section equation in closed form. The differential cross section obtained in this manner is compared by available numerical results and good agreement was obtained for TE and TM polarizations.

ISSN:0920-5071    

DOI:10.1163/156939398X00872

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A general formalism for electromagnetic surface waves associated with bianisotropic media is presented. Surface waves for some artificial bianisotropic media, namely uniaxial chiral medium, omega medium, and transversely uniaxial omega medium, are investigated. It is shown that a lossless uniaxial chiral medium cannot support a surface wave, while omega medium and transversely uniaxial omega medium can support surface waves under certain conditions and the corresponding dispersion relations for surface polaritons are derived. A general formalism for the analysis of surface waves for bianisotropic materials in the presence of microstrip is also given.

ISSN:0920-5071    

DOI:10.1163/156939398X00881

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Efficient evaluation of scattering by a material filled rectangular groove in an infinite conducting plane is formulated by matching waveguide mode expansions on both sides of the aperture. The technique is based upon a special form of equivalence and is shown to provide accurate bistatic results, with minimal complexity and computational effort, over a wide range of illumination angles, filler materials and groove dimensions.

ISSN:0920-5071    

DOI:10.1163/156939398X00890

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Thegeneral theory of the propagation of the electromagnetic field in omega media with cylindrical symmetry fed by an electric point-source has been addressed, and it has been established that the wave phenomena can be modeled in terms of the Kummer differential equation. This model leads to closed form analytical expressions for all the components of the electromagnetic field in far zone.

ISSN:0920-5071    

DOI:10.1163/156939398X00908

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Classification of bi-anisotropic media based on the structure of magnetoelectric coupling dyadics is proposed. It appears that the most general bi-anisotropic media can be modeled as composites of only a few basic idealized elements: for reciprocal materials, these elements are uniaxial helices and "hats," and in the case of non-reciprocal media, the fundamental particles are Tellegen elements (coupled electric and magnetic dipoles). In particular, it is shown that some composites with omega-shaped conductive inclusions embedded in an isotropic dielectric matrix can be considered as media with equivalent phantom chiral particles. Also, the mechanism is analyzed of the bi-anisotropic material based on magnetostatic-wave resonators.

ISSN:0920-5071    

DOI:10.1163/156939398X00917

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The statistical description of ocean clutter, which is made use of by the modern clutter suppression algorithms, is examined for sea states 0 and 4, for a grazing angle range 0.14°gr89.5° , for all polarizations, and for upwind and crosswind returns. The data for statistical description are obtained by a radar simulation program in which the electromagnetic pulses are traced in a user defined radar environment. In this simulation environment, the returns which are backscattered from the ocean surface are recorded individually along with their polarization, amplitude, phase, arrival time and Doppler shift. Based on the likelihood ratios of commonly used Rayleigh, Lognormal, Weibull and K-distribution families, the best fitting distributions to the observed data are chosen. When the results obtained are compared with those available in the literature, a good agreement is observed. Due to the limitations of experimental studies, the data necessary for the statistical description of the amplitude and the power of clutter are either not available or scarce for various sea states, grazing angles, polarizations and wind directions. For those cases where the statistical description is not available in the literature, the simulation program provides an inexpensive and reliable environment to obtain the best fitting distributions, which is an important ingredient of the modern clutter suppression algorithms.

ISSN:0920-5071    

DOI:10.1163/156939398X00926

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Interference effects are of utmost importance to the reliable design of satellite communication systems. In this paper, interference caused by differential rain attenuation from an adjacent Earth-space system operating at the same frequency is considered as dominant. In particular, a method to predict rain differential attenuation statistics, used for noise-dominant systems, is extended to include the general case when the calculation of the degradation of the total carrier-to-noise plus interference ratio (CNIR) under the presence of rain fading conditions, is necessary. The method is again based on a model of convective raincells and on the lognormal assumption for point rainfall rate statistics. The numerical results are concentrated on the analytical examination of the influence of various operational parameters upon the CNIR statistics and the subsequent outage performance of the system.

ISSN:0920-5071    

DOI:10.1163/156939398X00935

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939398X00944

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939398X00953

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor