| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a vehicle speed detector which can be installed on a vehicle easily by reducing a size of a Doppler sensor. SOLUTION: A radio wave emitting element 102 and a wave receiving element 104 are arranged while being shifted from an optical axis 126 of a lens 120 in a lens antenna. In this way, a transmission wave 128 can be radiated slantingly to a road surface 130 with the lens 120 kept horizontally to a vehicle body, and a reception wave 132 returning diagonally from an electric wave irradiated face on the road surface can be received in the wave receiving element 104. As the lens 120 and a case body 10 are held horizontally, a vertical size of a sensor unit is suppressed, and installation on a vehicle body bottom face is facilitated. The lens 120 is used in common for transmission and reception, so that a bottom area of the sensor unit is reduced, and because of this compactification, installation to the vehicle is facilitated.</p> |
