PROBLEM TO BE SOLVED: To detect the position of a vehicle on a road by burying the magnetostrictive resonator in or nearby the road in a specific direction on the assumption that it is detected by an antenna in the specific direction. ;SOLUTION: The magnetostrictive resonator 1 is buried at almost right angle to the road surface 2. A loop antenna 3 is installed under the vehicle body so that its loop face is in almost parallel to the road surface 2. In some case the loop face is set at almost right angle to the road surface. While relative relation like those is maintained, the burying angle of the magnetostrictive resonator can be varied variously or magnetostrictive resonators having different burying directions can be combined. The loop antenna 3 radiates electromagnetic wave of the resonance frequency of the magnetostrictive resonator 1 as a fixed short-time addressing radio wave and receives an electromagnetic wave that the magnetostrictive resonator 1 radiates at the mechanical resonance within a subsequent certain short time, and then the relative position of the loop antenna 3 to the magnetostrictive resonator 1 is detected from its received signal output.;COPYRIGHT: (C)1999,JPO
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