| 摘要 |
PROBLEM TO BE SOLVED: To provide a parabolic antenna that has a wind-endurance structure with respect to a wind from every direction without the need for extension work on a rooftop of a building. SOLUTION: An outer circumferential part of the main reflection mirror of the parabolic antenna is divided into a proper number of annular parts in the circumferential direction and a moving part of the main reflecting mirror which is a divided part is made to slide radially to be set to an escaped position or an exposed position. When a wind velocity and an atmospheric pressure measured by a meteorological instrument 1 exceed respectively a prescribed value for a prescribed time, a comparator section 2 gives a drive signal to a main reflection mirror drive section 5 via a drive control section 4, to move the moving part of the main reflecting mirror to a standby position and to reduce the diameter of the main reflection mirror. While the moving part of the main reflecting mirror is moving, a transmission system radio wave control section 8 causes the transmission to stop with a signal from the drive control section 4. When the diameter of the main reflection mirror is reduced, a sub reflection mirror is moved, as necessary, to a position of satisfactory communication efficiency by a drive signal from a sub reflection mirror drive section 6.
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