Polarization characteristics of VHF radio waves reflected by the Es-layer

Interference in VHF-TVs caused by the radio waves reflected from the ionosphere is a very serious problem in the area around Japan. The polarization rotation of the waves reflected by an E_s-layer are clarified by the measurement of a VHF television signal. Two types of polarization rotation are observed. In one case, the more common of the two, the polarization rotation varies randomly in a narrow range around an angle which rotate from the transmitted horizontal polarization in a short fading period. In the other case, which has a long fading period, the polarization rotation varies slowly in a wide range. It is shown that these polarization characteristics are caused by the Faraday effect in the ionosphere below the E_s-layer and in the E_s-layer itself