Estimation of Direction of Arrival of VHF Radio Wave by Interferometers

Abstract

In order to examine the direction of arrival of VHF radio waves dependent on the natural phenomena, the interferometers have been installed at Katsuyama, Chiba Prefecture and Numata, Gunma Prefecture. In this study, the radio wave at the frequency of 77.1 MHz transmitted from Tokyo Tower (assigned to FM broadcasting of the Open University of Japan) is observed. The interferometers consist of four Yagi antennas and estimate the directions of arrivals of the radio wave. The observational results show that the directions of the wave are affected by the disturbances in the ionosphere and the atmosphere. In this paper, the system of the interferometers is described and the examples of the observation results are presented.