What's microwave and doppler effect

The wave length of 300MHz to 3000MHz frequency, we call them microwave. This wave lenght is between Ultrashort wave and Infrared wave. Due to Earth's outer ionosphere can totally reflect the microwave, Microwave is one of best communication method.

Motion detectors are one of most widely used intrusion detection device for alarm system.  Now there are four kinds of motion detector that most of companies are providing; Active Infrared Motion Detector, PIR based Motion Detector, Microwave Motion detector, PIR + Microwave Motion Detector (Dual Technology).

Motion sensor is one of the core component to your intrusion alarm system. The passive infrared (PIR) motion sensors are widely used in anywhere of security system that requires motion detection. Unfortunately, due to the defects of infrared detection technology, majority of passive infrared (PIR) motion sensors may cause false alarm. More over, more and more people require the security alarm system protect the perimeter, as a result, some people request the security sensors can installed at outdoor, then normal PIR motion sensor can not completely meet this requirement, due to the false alarm (PIR sensors are sensitive to the temperature changes, they can not install in outdoor environment).