A Simple Method of Demonstrating the Circular Polarization of lonospherically Reflected Radio Waves

Abstract

SINCE the ionosphere is a doubly refracting medium, due to the influence of the earth's magnetic field, a plane-polarized radio wave incident normally on it is split into two elliptically polarized components of opposite rotational sense. For a certain range of frequencies, in the neighbourhood of the gyro-frequency, only one of these two components is reflected in strength, the other being strongly absorbed. In northern temperate latitudes this reflected component is of left-handed, approximately circular, polarization. In corresponding latitudes in the southern hemisphere the sense of the polarization is reversed.