Effects of ground reflection on the polarization of radio beacon transmission from ATS-6 satellite

Abstract

Stokes polarization parameters of linearly polarized ATS-6 radio beacon transmission at 40.016 MHz were recorded with a time-sharing radio polarimeter at Ahmedabad. The observed state of polarization showed quasi-periodic variations as a function of the orientation angle, which in turn, depends upon the total Faraday rotation in the ionosphere. The axial ratio was found to vary continuously from about 0.5 through zero to -0.5, and vice versa. These results are interpreted in terms of combination at the antenna of the direct and ground-reflected waves, taking into account their dependence on the orientation angle. It is concluded that for reliable polarization measurements a highly directive antenna with low side-lobe response is essential.