Theory of the modifications imposed on the ionospheric plasma by a powerful radio wave reflected in the D or E region

Abstract

The effect of a reflected wave on the absorption of a powerful plane radio wave vertically incident on the ionosphere is studied. For a single magnetoionic component wave the power absorbed per unit volume can vary considerably within the space of a few kilometres if the reflected component is strong. Two methods for calculating the reflexion coefficient are applied to the ordinary wave. The power absorbed is changed if an upgoing extraordinary wave is also present. The power absorbed causes an increase in the effective electron collision frequency which results in a change of the complex height of reflexion. This is studied first for an unmodulated wave. If the wave is amplitude modulated, the increase of collision frequency and thence the complex height of reflexion and the reflexion coefficient vary periodically in the modulation cycle. This effect is discussed for a wanted wave which is reflected in a region where the disturbing wave is heavily absorbed.