The reflexion of radio waves from a stratified ionosphere modified by weak irregularities

Consideration is given to the scattered wave which accompanies reflexion from a stratified ionosphere in which there are weak irregularities. By considering these irregularities to be confined to a thin layer near a given height, the possibility is examined that they might produce considerably enhanced scattering if they were situated near the reflexion level calculated on the basis of geometrical optics. It is found that they would not have a very much greater effect at this level. It is also shown that, if the electron collision frequency is of the order likely to be encountered in the real ionosphere, there would be little enhancement by ‘resonance’ effects of the kind suggested by Herlofson (1951).