PURPOSE: To intensively radiate infrared energy and reduce the capacity of an infrared ray source by providing a transmitter, a direction finding antenna, a receiver and a directional coupler and detecting the arrival direction of a missile.

CONSTITUTION: A transmitter 1 is connected to a directional coupler 2, which is connected to a direction finding antenna 3 and a receiver 4. The receiver 4 is electrically connected to an infrared radiator 6 via an infrared radiation controller 5. Electric power supplied too the antenna 3 is radiated from wave radiating elements as an electric wave and the wave reflected from a missile is received by the four wave radiating elements to be inputted to the coupler 2. The receiver 4 compares phase differences in wave signals received by the four wave radiating elements and the like with one another and derives the access direction of the missile from comparison. Information on the access direction is inputted to the controller 5 from the receiver 4. Infrared energy whose intensity is modulated by the controller 5 electrically feeds modulated signals, for example, to an arc lamp. The radiator 6 radiates infrared radiation energy in one missile access direction.