On the Propagation Anomalies of 100kHz Band Hyperbolic Navigation Systems Caused by a Huge Bridge-II : The Effects of Transverse Structure

Abstract

We have reported that the main towers of the huge suspension-bridge have been considered macroscopically as a couple of the vertical electric dipoles from analyzing the disturbances of the electric fields caused by Minami-Bisan Seto-Oohashi Bridge. In this paper, in order to study the effect of the reradiation from the structure of the bridge extending in the horizontal direction, the vertical electric field intensities of Decca Waves were measured near Akashi-Kaikyou Oohashi-Bridge. When two main-towers were built, the distur-bances of the field intensities appeared slightly. Secondly, as the hauling ropes were built between two main-towers, the shielding of the electric field was caused under the hauling ropes. Further, the sinusoidal-like variations of the erectric field intensities were also seen clearly on the transmitter side of the bridge. By the theoretical considerations, the static capacitance of the main-tower was about 0.003μF, and it became about 0.37μF after the hauling ropes were built. It will be concluded that the capacitance of the main-tower is increased apparently by the horizontal structure of the bridge such as hauling ropes or main cables, and consequently the main-towers radiate the strong secondary waves.