| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a lane mark device which prevents a bad influence due to 'creeping radio waves' and by which the position of as running vehicle can be detected precisely. SOLUTION: The radio-wave reflection type lane mark device is provided with a transmitting antenna 4, which transmits radio waves to a radio-wave reflecting body on a road and a receiving antenna 5, which receives reflected radio waves reflected by the radio-wave reflecting body, and the position of a running vehicle is detected on the basis of a received signal received by the receiving antenna 5. In the lane mark device, a protective cover 3 by which a part of the transmitted waves is passed or reflected so as to be incident on the receiving antenna 5 is provided in a position separated by a prescribed distance from the transmitting antenna 4 and the receiving antenna 5. The thickness and the permittivity of the protective cover 3 are selected on the basis of the distance between the transmitting antenna 4 and the receiving antenna 5 and on the basis of the wavelength of the transmitted radio waves and the distance between the inner face of the protective cover 3 and the transmitting face 4a of the transmitting antenna 4 and the receiving face 5a of the receiving antenna 5 are set in such a way that creeping radio waves of the receiving antenna 5 from the transmitting antenna 4 and the transmitted radio waves reflected by the protective cover 3 interface so as to be offset.</p> |
