Effect of Weather on Over-the-horizon Propagation of UHF Radio Waves over the Japan Sea

Abstract

Recently, the electromagnetic environment in the UHF television band has changed significantly in Japan. Digital broadcasting has spread, but radio disturbance occur from spring to fall. This phenomenon is caused by ionospheric propagation of the Es layer or duct propagation in the troposphere. We have steadily observed UHF radio waves at Ishikawa National College of Technology in Tsubata since 2005. UHF radio waves are received from Matsue city and Korea, which are over-the-horizon distances away from Tsubata. Therefore, we researched the relations between the wave receiving statuses of channels 41, 43, and 45 from Matsue city and the season and weather, and we found that we received the most radio waves in summer and in fine weather. Therefore, this phenomenon may be due to the duct propagations in the troposphere.