摘要:

The scattering of an obliquely incident and arbitrarily polarized plane wave by impenetrable (e.g., metallic) or penetrable (i.e., chiral) cylinders coated with an arbitrary number of layers of different chiral materials is considered. The constitutive relations within each homogeneous layer are given in terms of the chirality admittance. A cylindrical wave expansion is used to express the fields in each layer and in free-space, while a chain-matrix algorithm is used to expedite the numerical evaluation of the scattered field. The radar cross-section is analyzed over a wide frequency band.

ISSN:0920-5071    

DOI:10.1163/156939392X01390

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An integral equation and method of moments/Green's function solution to the problem of scattering by a chiral cylinder of arbitrary cross section in the presence of a perfectly conducting half-plane is presented. The volume equivalence theorem for chiral media is used to formulate a pair of coupled vector integral equations for the equivalent electric and magnetic volume polarization currents representing the chiral cylinder. The presence of the half-plane is accounted for by including the half-plane Green's function in the kernel of the integral equations, and efficient techniques for accurately evaluating the integrals in this Green's function are presented. Numerical results illustrate that a chiral cylinder surrounding the half-plane edge can significantly modify the scattering from the edge. The chiral cylinder is also seen to produce significant cross-polarized scattered fields, which are a direct result of the rotation of field polarization in a chiral medium.

ISSN:0920-5071    

DOI:10.1163/156939392X01408

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Integral equations are obtained for the electromagnetic (EM) scattering by an inhomogeneous, isotropic, three dimensional chiral body. The chiral body is assumed to be in free space, and it can be attached to a perfect electric conducting (PEC) body. The integral equations are obtained with the help of vector-dyadic identities and the free space dyadic Green's function. These equations are expressed in terms of a volume integral with the electric field as the unknown and surface integrals where the tangential components of the electric field and its curl are the unknowns. The integral equations are then transformed into a linear system of simultaneous equations by means of the moment method technique. Expressions for the scattered field in the far-zone are also obtained by replacing the dyadic Green's function and its curl with their large argument approximations. Furthermore, closed form expressions are obtained for the fields and dipole moments induced inside an electrically small, homogeneous chiral sphere where it is assumed that the fields are constant. Finally, closed form expressions and numerical results for the fields scattered by the small chiral sphere and its bistatic echo area are also obtained.

ISSN:0920-5071    

DOI:10.1163/156939392X01417

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper a formulation for the solution of the electromagnetic field in stratified structures with an istropic chiral grounded slab under planar electric excitation conditions is presented. The development of the solution is obtained by using the two-dimensional (Fourier) transform applied to the partial differential equations describing the electromagnetic field, expressed in terms of dyadic electric Green's function. Moreover, a spectral equivalent circuit representation of the solution, separated into its spectral transverse electric (TE) and transverse magnetic (TM) components (with respect to the vertical direction), is given. Noteworthy reciprocity properties among the elements of the spectral dyadic Green's function are presented together with the determination of the degrees of freedom of the structure. Finally, an example of this theory applied to an electric vertical point source disposed at the interface plane between the chiral slab and the homogeneous istropic upper half-space is given with the evalution of the radiated pattern.

ISSN:0920-5071    

DOI:10.1163/156939392X01426

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Recently, we introduced the idea of chirostrip antennas which are microstrip radiators with chiral materials as substrates and/or superstrates. Owing to the handedness of chiral substrates, novel features are associated with this type of antenna. In this paper, the problem of chirostrip line antennas is analyzed in detail. These antennas consist of an electric line source printed on top of a grounded chiral slab. Both the surface wave and radiation modes of such substrates are obtained and their important features are discussed. Excitation of these surface waves and radiation by the line source are studied and their notable characteristics, such as the power and polarization state of the radiation fields, and the power carried by surface waves, are addressed. It is found that for the two-dimensional chirostrip antenna the chirality can, under certain circumstances, decrease the undesirable surface-wave power and increase the radiated power, thus giving rise to higher radiation resistance and radiation efficiency in these antennas. Such designs would lead to more efficient antennas with wider bandwidth. The physical understanding gained from the analysis of such antennas can help us to introduce novel designs for more complex printed-circuit and conformal antennas utilizing chiral materials. It is concluded that chiral materials can potentially substitute some of the conventional materials commonly used in microwave components and will open new chapters in the design of novel microwave and millimeter-wave devices.

ISSN:0920-5071    

DOI:10.1163/156939392X01435

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0920-5071    

DOI:10.1163/156939392X01444

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor