Hindawi Publishing Corporation
International Journal of Antennas and Propagation
Volume 2011, Article ID 409764, 6 pages
doi:10.1155/2011/409764
Research Article
Scattering of a Plane Wave by an Anisotropic Plasma-Coated
Conducting Sphere
You-Lin Geng
Institute of Antenna and Microwaves, Hangzhou Dianzi University, Xiasha, Zhejiang Province, Hangzhou 310018, China
Correspondence should be addressed to You-Lin Geng, gengyoulin@yahoo.com.cn
Received 19 June 2011; Revised 18 August 2011; Accepted 24 August 2011
Academic Editor: Miguel Ferrando
Copyright © 2011 You-Lin Geng. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The electromagnetic field in homogeneous plasma anisotropic medium can be expressed as the addition of the first and second
spherical vector wave functions in plasma anisotropic medium. The tangential electromagnetic fields are continued in the
boundary between the homogeneous plasma anisotropic medium and free space, and the tangential electrical field is zero in
the surface of conducting sphere. The coefficients of electromagnetic fields in plasma anisotropic medium expanded in terms of
spherical vector wave functions in plasma anisotropic medium are derived, and then the coefficients of scattering fields in terms of
spherical vector functions in free space can be obtained. Numerical results between this paper and hybrid finite element-boundary
integral-multilevel fast multipole algorithm (FE-BI-MLFMA) are given, and they are in agreement very well. Some new numerical
results of a plane wave scattering by an anisotropic plasma-coated conducting sphere are obtained.
1. Introduction
Plasma represents a medium of gas in highly ionized state,
and it is a neutral mixture of free ions, electrons, and mole-
cules. For example, when the ionosphere and the sheath of
satellite and missile come into atmosphere, the y are consider-
ed to be plasma in nature. When there is an externally applied
magnetic field, a plasma exhibits anisotropic behavior and its
permittivity takes a tensor form. The elements of the permit-
tivity tensor are complex functions of wave, plasma, gyro and
collision frequencies [1–3]. Wave propagation in, and scatter-
ing by, an anisotropic medium is nonreciprocal, and its anal-
ysis becomes very difficult even when the plasma is treated
as an incompressible gas [1–4].
The interaction between e lectromagnetic wave and an-
isotropic medium has attracted much interest. It is simply be-
cause there are many natural and artificial anisotropic mate-
rials, and they are frequently used in optical signal processing
(such as constructing signal processing elements at optical
frequencies), the radar cross-section control for various
objects or scatterers, antennas or airborne radomes, optical
fibers, developments of certain types of radar absorbers, and
high-perfor m ance microstrip antenna designs where the
substrates of this nature are desirable.
One of the basic problems in investigating waves in aniso-
tropic media is to accurately and efficiently characterize elec-
tromagnetic scattering. Scattering by homogeneous aniso-
tropic objects has attracted considerable interests in recent
years. Numerical methods based on integral equations [5]as
well as differential equations [6] were developed, and the
analytical method based on eigen vector wave functions [7]
was also adopted to characterize this kind of problems. Al-
though the efforts in the past were primarily spent on two-
dimensional (2-D) geometries, some progresses have been
made in the analysis of three-dimensional (3-D) anisotropic
scatterers using the method of moments (MoM) [8, 9], the
couple dipole approximation method [10], hybrid finite
element-boundary integral-multilevel fast multipole algo-
rithm (FE-BI-MLFMA) [11], integral equation method [12],
and Fourier transform, eigenvalue and eigen functions,
spherical vector wave functions solution [13–15]. In the pre-
sent study, the simple and efficient method proposed in [13]
will be employed to tackle the scattering problem associated
with an anisotropic plasma-coated conducting sphere by a
plane wave.
Electromagnetic fields in plasma anisotropic medium
andfreespacecanbeexpandedintermsofsphericalvector
wave functions in plasma anisotropic medium and free space,