Electromagnetic radiation from line sources embedded in a uniaxial dielectric or plasma half‐space backed by a medium of finite conductivity

摘要

This paper treats the problem of electromagnetic radiation from the electric and magnetic line sources embedded in a uniaxially anisotropic dielectric or plasma half‐space backed by a finitely conducting medium. The anisotropy of the uniaxial medium is taken along the x direction and the line source is aligned parallel with the z axis. For the envisaged geometry, E and H modes are independently excited by a magnetic and an electric line source, respectively. Expressions for the far‐zone radiation field and the radiation pattern are obtained via the saddle‐point technique of integration. It is noted that the radiation from an electric line source remains unaffected by the anisotropy of the medium and possesses only a radial component of the Poynting vector. In contrast, the radiation from a magnetic line source not only depends on the anisotropy of the medium but has, in addition to the radial component, a circumferential component of the Poynting vector indicating deviation of the resultant energy flow from the radial direction. Numerical results for the radiation pattern and also for the angle of deviation of the power flow from the radial direction, for the magnetic line source, are presented for a wide range of parameters characterizing the anisotropy of the uniaxial medium, the location of the line source, electron‐plasma density, and the conductivity of the half‐space backing the uniaxial medium. It is revealed that in the case of a uniaxial plasma or dielectric backed by a perfect conductor, the radiation has a finite strength of unity both in directions ϑ=0 and ϑ=π, in contrast to the case of a medium backed by a finitely conducting medium.