Electromagnetic scattering by a uniaxially anisotropic sphere

The problem of electromagnetic scattering by a uniaxially anisotropic sphere is studied for both dielectric and absorbing cases. The fields of the TM to rˆ wave inside a uniaxial sphere can be derived to be expressed in series of Bessel functions, as in the isotropic case, but with the order of function determined by the anisotropic ratio (AR=ε_θ/ε_r). For the TE to rˆ wave, the uniaxial medium can be treated as an isotropic material characterised by ε_θ only, which is the permittivity parallel to the boundary surface of the medium. The effects of uniaxial anisotropy on the radar cross section (RCS) are also considered. It is found that the uniaxial anisotropy greatly influences the scattering behaviour of a spherical dielectric object. For an absorbing sphere, the uniaxial anisotropy no longer plays a significant role and the dependence of the RCS on uniaxial anisotropy is found to be predictable. Details of theoretical treatment and numerical results are presented