| 摘要 |
<p>The device, which can be used for taking pictures on the public thoroughfare, comprises a mobile equipment provided with a transmitter on a first carrier frequency, with a transmitting antenna driven by the transmitter and with a receiving antenna (20), and a gathering station provided with an antenna (16) for reception at the first frequency and with an antenna (18) for sending back a return signal at a second frequency. The transmitter is tuned to a carrier frequency selected so that the radius of the Fresnel ellipsoid is less than the distance between the antenna (14) and the closest reflecting obstacle and means being provided in the mobile equipment for slaving the transmission lobe of the transmitting antenna (14) to the receiving antenna (16) of the gathering station, the said means using the return signal to the mobile equipment. <IMAGE></p> |
