Microwave Sensor

摘要

According to one embodiment, a microwave sensor includes: a first directional coupler (DC 1 ) connected on a path of a transmission antenna unit (A 1 ); a second directional coupler (DC 2 ) connected on a path of a reception antenna unit (A 2 ), and a determination unit ( 4 ) that obtains, based on monitor outputs from these, a scattering parameter S₁₁ corresponding to a reflectance property at the transmission antenna unit (A 1 ) and a scattering parameter S₂₁ corresponding to a transmission property from the transmission antenna unit (A 1 ) to the reception antenna unit (A 2 ), and outputs an alarm signal (Dout 2 ) when at least one of the scattering parameter S₁₁ and the scattering parameter S₂₁ continuously exhibits a value outside its respective pre-set range over a predetermined period of time.