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The vehicular collision avoidance millimeter-wave radar that uses an FM-pulse Doppler method is proposed. This radar is constituted with the FM-CW radar method and the pulse Doppler radar method. This radar method has combined the advantages that the precision of the measurements of distance and speed of the target that the FM-CW radar method provides, and the low target mis-recognition probability that the pulse Doppler radar method provides. The millimeter-wave radar using this method was produced using comparatively simple circuits The experimental data that was obtained with this radar and with the FM-CW radar are compared with each other. The effectiveness of the FM-pulse Doppler method was investigated using data obtained from on the road environment using a target vehicle and some objects.

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.

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.