Principle of microwave detector in three-tech passive infrared detector
The Doppler principle in physics tells us that in the microwave band, when transmitted at one frequency, within the range covered by microwave energy, when there is a moving object, it will be reflected at another frequency. There is a frequency difference in the reflection frequency. This frequency difference is related to many factors, including the speed of the moving object and the radial angle of the detector. The microwave detection principle is relatively complicated in theory. However, in the three-technology infrared detector, in addition to the basic concepts of microwave detection, we also need to understand that the transmission of microwaves has the permeability to buildings. Improper sensitivity adjustment may radiate outdoors, which may cause false alarms.