An exceptionally high radar frequency of 35 GHz has the ultrashort wavelength of about 1 cm, so the antenna size can be reduced to headlight proportions. The transmitter/receiver array is a pair of rectangular parabolic reflectors enclosed by polystyrene radomes protruding through the car's radiator grill. Effective range is restricted to around 100 meters, regarded as sufficient for early warning even at high cruising speeds. This reduces signal clutter from unwanted echoes on the road farther ahead. The fixed beam has an angular width of only 2.4 deg, which not only concentrates the radiated power but also limits radar vision to a straight-ahead path. In the vertical plane the beam is narrowed to 3.4 deg to avoid responses from bridges and other overhanging structures. A simple arrangement minmizes false echoes on curves, where the 100-meter beam might respond to stationary objects like trees and houses on left-hand bends, and traffic in adjacent lanes on right-hand ones. The beam range is effectively reduced according to the steering angle of the car wheels. Systems described are by the Stuttgart firms of Robert Bosch and Daimler Benz. Both systems measure distance to the car ahead; an on-board computer calculates the instantaneous safe following distance, considering the car's own speed, road condition (dry, wet, or snow), and driver reaction time. Displays use light-emitting diodes.

Media Info

  • Pagination: p. 78-80
  • Serial:
    • Automotive Engineering
    • Volume: 86
    • Issue Number: 7
    • Publisher: Society of Automotive Engineers (SAE)
    • ISSN: 0098-2571

Subject/Index Terms

Filing Info

  • Accession Number: 00183241
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Dec 12 1978 12:00AM