Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Patent
1998-12-07
2000-05-02
Gregory, Bernarr E.
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
342 27, 342 71, 343711, G01S 7521, G01S 1393, H01Q 127
Patent
active
060577975
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a radar sensor for use in motor vehicles, which has at least one antenna element for emitting radar beams and, physically separated therefrom, at least one antenna element for receiving the radar beams reflected by one or more objects.
BACKGROUND INFORMATION
Radar sensors can be used in motor vehicles preferably for measuring distances and relative velocities of vehicles traveling one behind the other. Such a proximity radar system is usually referred to in the literature as an Autonomous/Intelligent Cruise Control (AICC/ICC) or Adaptive Cruise Control (ACC). The system generates either a collision warning signal or automatically controls the brakes or the drive of the motor vehicle if the distance to a vehicle traveling ahead drops below a minimum permissible value.
European Patent No. 0 568 427 describes a radar sensor, in which a plurality of transmitting antenna elements and a plurality of receiving antenna elements are arranged separately from one another. The transmitting antenna elements generate a multibeam radiation pattern, and an array of receiving antenna elements installed in front of the transmitting antenna elements receives the radar beams (radar echos) reflected from one or more objects. The receiving elements are arranged in the transmission range of, and oriented in the same direction as, the transmitting antenna elements. If both the radar transmitter and the radar receiver are to be supplied from the same oscillator to minimize costs, relatively long high-frequency lines are needed in the case of the known antenna arrangement, since the outputs of the receiving antenna elements must be run via long, circuitous routes to a common oscillator arranged near the inputs of the transmitting antenna elements. Long lines, on the other hand, have the disadvantage that they generate relatively high losses.
An object of the present invention is to provide a radar sensor which requires the shortest possible lines in order both to supply the transmitting antenna element with the carrier signal of an oscillator and to demodulate the output signals of the receiving antenna element with the same oscillator carrier signal.
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved by arranging at least one receiving antenna element is arranged outside the radiation pattern of at least one transmitting antenna element. The transmitting and receiving antenna elements are oriented in different directions. An arrangement is provided to deflect the reflected radar beams onto the receiving antenna element and/or the radar beams emitted by the transmitting antenna element in a desired direction. With this arrangement of the transmitting and receiving antenna elements only very short connecting lines to a common oscillator are needed. Due to the separation of the transmitting and receiving antenna elements, the use of loss-producing components (e.g. circulators, ring hybrids), which separate transmitted signals from received signals in the case of radar sensors having antennas with both transmitting and receiving functions, can be omitted.
It is also advantageous to orient the receiving antenna elements orthogonally to the transmitting antenna elements and to provide a deflecting mirror to deflect the reflected radar beams onto the at least one receiving antenna element. To receive the reflected radar beams (radar echo), the use of at least three receiving antenna elements is advantageous. It is also recommended that one or more quasi-optical lenses be provided for focusing the transmitted and reflected radar beams. In another embodiment, two quasi-optical lenses can be arranged next to one another in a plane with the at least one transmitting antenna element being arranged in the focal plane of one of the two lenses and the deflecting mirror being oriented to the focal plane of the other quasi-optical lens so that the mirror deflects the reflected radar beams focused by this lens onto the at least one receiving antenna ele
REFERENCES:
patent: 3772690 (1973-11-01), Nations
patent: 3778823 (1973-12-01), Sato et al.
patent: 3848914 (1974-11-01), Wathen
patent: 3935559 (1976-01-01), Straffon et al.
patent: 5670962 (1997-09-01), Henderson et al.
patent: 5696515 (1997-12-01), Zyren et al.
Merrill I. Skolnik, "Introduction to Radar System," (McGraw-Hill, New York, 1980, second edition), p. 254, 1980.
Gregory Bernarr E.
Robert & Bosch GmbH
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