|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1994 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1993 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1992 : ¥700,000 (Direct Cost : ¥700,000)
In this thesis, the first chapter gives a review of the progress of historical research of radio wave application and its assignment.
In the second chapter, the behavior of the Loran-C wave near a coast line is discussed. As a ship approaches the seashore, the secondary wave of the Loran-C wave is reradiated from land, and the primary wave and secondary wave overlap each other. Then, the velocity of radio wave resulting from superposition of the primary wave and the secondary wave gets faster and slower in an interval of 750-800m. These results are also interpreted by the numerical calculations. In the third and fourth chapter, the disturbance problems of Decca waves and the Loran-C waves caused by huge bridges are discussed. In order to elcidate theoretically the mechanism of the secondary radiation from Seto-Ohashi-Bridge, several experiments were carried out by using Decca waves. According to these results, a couple of high bridge-towers could be considered to be vertical electric dipole antennas. From the measurements of electric field strength of Decca waves, the static capacitance of each pair of high bridge-towers, which are modeled as a vertical electric dipole antennas, is about 0.2muF.Hence, it is possible to establish an antenna model of the bridge consisting of two parallel vertical electric dipole antennas with 0.2muF static capacitance in each. Furthermore, in order to investigate the magnitude of positioning errors, the phase measurements of Loran-C waves with the receiver, referenced to a highly stable Rubidium beam oscillator, were carried out near Seto-Ohashi bridge. From the results of measurement, it could be observed that in a wide region on both sides of the bridge far from 200m to 1,500m, the phase errors vary from <plus-minus> 0.2mus to <plus-minus> 0.4mus in time. These phase errors correspond to <plus-minus> 60 - <plus-minus> 120m in distance. Finally this thesis is concluded in the fifth