Abstract
Vehicular collision avoidance radar systems using millimeter-wave have been developed in recent years. 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. The pyramidal horn and the radio frequency 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. Therefore, it is easy for the OP antenna to increase the number of beams and to extend the target detection angle range. We have improved the OP antenna in order to extend the target detection angle range and to miniaturize the radar head. The OP antenna was designed to radiate four beams so that the target detection angle range might become 12 degrees. We have produced the OP antenna and measured its characteristics. Both measured results of the radiation patterns and the antenna gains are almost corresponding to the calculated results. Consequently, it was confirmed that the OP antenna is useful for vehicular collision avoidance radar systems.