I. Theory of radio reflections from meteor trails: I

Abstract This paper deals with the evaluation of the reflection coefficient for backward scattering of an electromagnetic wave from a column of ionization having cylindrical symmetry. The application of the theory to meteors thus depends on the assumption that a meteor instantaneously forms a narrow column of ionization which subsequently diffuses radially. The theory predicts two qualitatively different categories of meteor echoes, depending on whether the electron line density, α, is greater or less than about 1012 per cm, the properties of which may be summarized as follows: If the incident electric vector is parallel to the axis of the trail (parallel scattering) it is sufficient to assume that the electrons scatter coherently and independently, each contributing an amount 4π(e 2/mc 2)2 to the backward scattering cross section. As the column expands radially, the echo amplitude decreases, the form of decay being exponential if the electron density is a Gaussian function of radius. When the incident el...