The application of the magneto-ionic theory to the ionosphere

Abstract

There have been published a number of discussions of the magneto­-ionic theory of the reflection of wireless waves from the ionosphere, neglecting, more or less, the effects of collisional friction. Taylor has published a series of curves indicating the effect of selected constant values of friction at various frequencies, and the author has discussed some general properties of the formulæ of the magneto-ionic theory when electronic collisions are taken into account. In the present paper an attempt is made to investigate, by methods of approximation, the general problem in which both ionization density and collisional frequency vary with height, and to show how the phenomena depend on wave frequency. Attention is confined, however, to vertical propagation. In order to bring out the principles of the discussion before going into the details of the magneto-ionic theory, the conditions when the earth’s magnetic field is neglected are discussed in 2. The magneto-ionic theory itself is investigated in 3 in order to see how simple formulæ, derivable immediately from the dispersion theory of Lorentz, may, with due care, be applied to circumstances differing widely from those he originally contemplated. 4 and 5 deal respectively with the heights of reflection and the absorption of the magneto-ionic components. In 2-5 it is assumed that reflection from the ionosphere is gradual ( i. e ., refractive), but in 6 consideration is given to specular reflection of very long waves.