Patent ID: 8830114

Claim:
A mobile object detecting apparatus, comprising: first radiation detecting means for radiating an electromagnetic wave and detecting a standing wave which is generated due to reflection of the radiated electromagnetic wave at an object; second radiation detecting means for radiating an electromagnetic wave having the same frequency as the electromagnetic wave radiated by the first radiation detecting means such that the radiated electromagnetic wave passes near a point in the first radiation detecting means from which the electromagnetic wave is radiated, and detecting a standing wave which is generated due to reflection of the radiated electromagnetic wave at an object; wherein the mobile object detecting apparatus is configured to detect a movement of an object or the presence or absence of a mobile object based on the standing wave detected by the first radiation detecting means and/or the standing wave detected by the second radiation detecting means, the second radiation detecting means radiates the electromagnetic wave in a direction opposite to a direction in which the first radiation detecting means radiates the electromagnetic wave, and reflects the radiated electromagnetic wave at a reflective member with an elliptical cross section to be directed to the point in the first radiation detecting means from which the electromagnetic wave is radiated, the elliptical shape of the reflective member has two focal points at points in the first and second radiation detecting means from which the electromagnetic waves are radiated, and a distance, over which the electromagnetic wave radiated by the first radiation detecting means travels until it reaches near the point in the first radiation detecting means from which the electromagnetic wave is radiated, corresponds to a distance of an integral multiple of a wave length of a half cycle of the electromagnetic waves radiated by the first and second radiation detecting means plus a wave length of a predetermined period which is smaller than the half cycle.