PURPOSE: A microwave sensor is provided to obtain a uniform gain regardless of an azimuth by including a single transceiver antenna and a circuit which is operated by the single transceiver antenna. CONSTITUTION: A power divider divides a microwave signal. An antenna transmits the divided microwave signal to the outside and receives the microwave signal reflected by an object. The antenna is composed of an antenna pin(542) which is located in the center of a ground plate(541) and a metal wall(544) which forms the circumference of the ground plate. A mixer outputs an intermediate frequency by detecting difference between the signal from the power divider and the microwave signal received from the antenna.
