Modeling of radiated characteristics of plasma-surrounded antenna

The radiation from a spherical antenna immersed in a plasma shell has been studied. In infinite plasma shell, when the electromagnetic wave frequency is greater than the plasma frequency, the electromagnetic wave can through the plasma layer enclosing the antenna. On the contrary, the radiation cannot pass the plasma layer. However, when the boundary conditions are considered, a strange phenomenon, that the radiation can not only go across the plasma layer but also get enhanced by this plasma layer in some electromagnetic wave frequencies that much less than the plasma frequency, will happen. For studying this phenomenon, some partial differential equations and its definite conditions has been constructed by using the magnetohydrodynamics theory. In order to solve these equations, a simulation model has been established. Through simulation studies, the conditions of radiation enhancing has been found. The conditions of this phenomenon depend on the radius of the spherical antenna, the thickness of the plasma shell and the thickness of plasma sheath around the antenna. When these conditions are properly chosen, the enhanced radiation will be obtained in some certain frequencies. Furthermore, the relationship between these parameters and the radiation of the antenna has been presented.