Results of simultaneous measurements of absorption and polarization of radio waves reflected from ionosphere

A review of experimental data shows that the effective electron collision frequency in the lower ionosphere has a significant effect on the polarization of reflected radio waves; diurnal variations of absorption and polarization are statistically correlated. For a constant plasma frequency, an increase in absorption leads to an increase in the ratio of polarization-ellipse (PE) axes, and to a rotation of the PE major axis toward the east-west line (for an ordinary wave). The correlation coefficient of diurnal variations of the absorption and polarization characteristics was found to equal 0.7, on the average. It is also shown that, during a solar eclipse, the PE axis ratio increases and the orientation of the PE major axis is unstable.