Abstract: An antenna device has first and second radiation patterns different from each other, the first radiation pattern having a main lobe, and a side lobe with a first gain, and the second radiation pattern having a main lobe, and a side lobe with a second gain different from the first gain. The signal analyzer detects a first signal level of a radar wave received when the first radiation pattern is set for the antenna device, and detects a second signal level of a radar wave received when the second radiation pattern is set for the antenna device. When a difference between the first and second signal levels is smaller than a threshold, the obstacle identifier determines that the reflective object is an obstacle, and otherwise, the obstacle identifier determines that the reflective object is not an obstacle.

Abstract: A vehicular apparatus is provided with a radar device. A station apparatus has a stop position for the vehicular apparatus. The station apparatus is provided with a signal source located at a position and transmitting a radio signal to the radar device. A receiver circuit of the radar device receives a radio signal from a signal source to output a received signal, when the vehicular apparatus stops at the stop position. A signal processing circuit of the radar device estimates distance and direction of the signal source with respect to the radar device based on the received signal. A control circuit of the radar device calibrates the receiver circuit, or the signal processing circuit based on known distance and direction of the signal source with respect to the radar device of the vehicular apparatus stopping at the stop position, so as to minimize errors of the estimated distance and direction.