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Vehicular collision avoidance radar systems using millimeter-wave have been developed in recent years. Because of their simple structures, a microstrip antenna or a lens antenna is often used as the radar antenna. However, the antenna efficiencies of these antennas are low, in general. Therefore, the types of antenna that have small antenna aperture are difficult to obtain high antenna gains. In addition, it is difficult to radiate many beams at narrow beam intervals with a lens antenna. We developed an offset paraboloidal reflector antenna (the OP antenna) for the vehicular collision avoidance radar. This antenna consists of one pyramidal horn antenna and one offset paraboloidal reflector. They pyramidal horn and the radio frequency unit (the RF unit) of the radar are fixed in the radar head. To scan the beam, only the reflector is rotated. Using a reflector-rotating mechanism, the OP antenna can radiate many beams toward different directions.

This paper is concerned with a scan laser radar sensor used to measure distance. It s a basic component of a vehicle distance warning system or an intelligent cruise control system. An intelligent cruise control system requires not only the distance to the object, but also the ability to detect movement of the preceding vehicle and the existence of any other nearby obstacle. However conventional radar sensor mainly fixed beam technology and measure only distance. Therefore, it s insufficient for the application to an intelligent cruise control system. Our newly developed scan laser radar transmits an extreme narrow beam and scans both transmission direction and reception direction simultaneously at a high measurement time rate. This scan laser radar can measure the lateral position of objects with high accuracy and good reconstruction level.

In vehicle distance warning systems using fixed beam laser radar false alarms often occur on curved roads. To solve these problems, we attempted to detect the target vehicle correctly by using a scanning laser radar on curved roads. This scanning laser radar has the advantage that it is able to measure the distance and direction of obstacles on roads. In this paper, we explain the following three items. The first is the configuration of the experimental system which we developed. The second is the method of target vehicle detection by using reflectors located along roads. The third is the performance of this experimental system.

An offset paraboloidal reflector antenna for vehicular collision avoidance radar is designed and evaluated. The antenna is designed to use at 77GHz band, and to have suitable gain and beamwidth for the vehicular collision avoidance radar. The properties measured and calculated are compared and confirmed to agree well. The offset paraboloidal reflector antenna is low-loss and has large degree of freedom of antenna design, compared with such as a microstrip antenna. So, using this type of the antenna for the radar system contributes to miniaturize, to make light weight, and to be easily mass-produced of the radar system.