Reflection of Electromagnetic Waves from Inhomogeneous Plasma

摘要

Reflections of electromagnetic waves and signals from an inhomogeneous, lossy, dispersive, anisotropic medium are discussed. Discussion is mainly confined to one dimensional stratified medium and high frequency waves. The medium can be either a dielectric or a plasma region. Reflection of a monochromatic electromagnetic wave from a stratified medium is considered. To determine whether the weak reflections of order 1/K come from the bulk effect of inhomogeneity of the medium or from the discontinuities of the gradients of the refractive index, a straightforward field analysis is used in which the behavior of the refractive index in the neighborhood of a gradient discontinuity is controlled by adjustable parameters. An integral equation is derived from the wave equation and from it, a variational expression is obtained for the correction term to the WKB approximation result for the reflection coefficient. The reflection of a turned-on sine signal from a plasma medium is considered. In the plasma, the electron density varies linearly in one direction. Complex integration is used to calculate the reflected signal.