摘要:

Novel classes of bianisotropic media, termed semi-chirals, plano-chirals, plano-semi-chirals and axi-chirals, are presented based on a reconsideration of the concept of chirality in multi-dimensional space. The constitutive dyadics for these media are derived formally, using the invariance and non-invariance properties for the media for a set of affine reflection transformations. Scalarity and pseudo-scalarity of the constitutive parameters for these reflection transformations are investigated. Examples are given of structures that enable the practical design of such media to be made.

ISSN:0920-5071    

DOI:10.1163/156939397X00549

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The line parameters (such as propagation constants, C and L) of a multiconductor transmission line in a multilayered medium show statistical variations, due to variations on the design parameters of the line. This statistical behaviour is analysed in the quasi-TEM approximation using a sensitivity based technique, requiring the computation of the derivatives of the line parameters with respect to the design parameters. Since we also need this information for most efficient optimisation techniques, we can perform optimisation and statistical analysis in one run. We compute the derivatives using adjoint style sensitivity evaluation. From the original quasi-TEM integral equation we derive a new integral equation with same kernel but with different right-hand side and with new unknowns equal to the derivatives of the original ones. All derivatives can be obtained with only one inversion of the integral equation.

ISSN:0920-5071    

DOI:10.1163/156939397X00558

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Analytical models for small Ω-shaped conductive particles in free space or embedded in isotropic materials are presented and discussed. The electromagnetic analysis is based on the antenna theory for circular loop antennas and dipole wire antennas. Analytical expressions for the polarizabilities valid in the frequency area covering the two lower resonances are given. Mutual coupling between two portions of the particle: the loop and the straight wire is considered in terms of the mutual impedance, which is analytically calculated with the use of the induced electromotive force method. Approximate analytical expressions are compared with numerical simulations and are seen to be in good agreement. The results can be used in analytical modeling of omega and chiral composite materials and in the antenna theory.

ISSN:0920-5071    

DOI:10.1163/156939397X00567

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Effective field method is applied for the calculation of the phase velocities and attenuation factors of plane monochromatic electromagnetic waves in a dielectric medium with an array of spherical inclusions. The results of calculation are investigated in a wide region of the volume concentrations of inclusions and frequencies of the exciting field. The influence of the space distribution of the inclusions on the effective velocities and attenuation factors is studied. The obtained results together with experimental data given in literature allow to evaluate the region of the application of the effective field method for the solution of the considered problem.

ISSN:0920-5071    

DOI:10.1163/156939397X00576

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The input impedance of a thin cylindrical wire antenna kept horizontally above a lossy earth (modeled as a half-space) is calculated by solving the electric field integral equation for the antenna current using the method of moments (MoM). Coupled horizontal wire antennas kept at the same height from the air-earth interface are analyzed by solving the corresponding zero and first phase sequence current integral equations. Mutual impedance results for broadside and collinear configurations are presented. The earlier used MoM solution is used to calculate the input impedance of a horizontal wire antenna above a two-layered earth. This investigation is useful to determine the sensitivity of the antenna impedance to the changes arising from subsurface anomalies. The Sommerfeld-type integrals encountered in these analyses are evaluated by an accurate Gaussian integration method.

ISSN:0920-5071    

DOI:10.1163/156939397X00585

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939397X00594

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939397X00602

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor