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Microwave Sensor vs PIR Sensor-Difference between Microwave Sensor and PIR Sensor

This page compares Microwave Sensor vs PIR Sensor and mentions difference between Microwave Sensor and PIR Sensor (Passive Infrared Sensor).

Both are used as occupancy sensors but their principle of working are different. Microwave sensor is active sensor as it emits microwave signal for detection. PIR sensor is passive sensor as it senses infrared signal emitted by various objects including human body.

Microwave sensor

Microwave Motion Sensor

The figure-1 depicts microwave motion sensor. As shown it emits frequency in the microwave region and will analyze the returned/reflected microwave frequency for determining motion.

PIR sensor | Passive Infrared Sensor

PIR motion sensor

PIR sensor houses pyro-electric sensor as shown in the figure-2. PIR sensor generates energy when exposed to heat. Human or animal body radiates energy in the form of infrared radiation. Hence when human/animal come in the range of PIR motion sensor, it receives thermal energy and hence motion is detected by the sensor.

Following points summarize difference between microwave sensor and PIR sensor.
➨Microwave sensor has higher sensitivity than PIR sensor.
➨Microwave sensor has higher coverage range than PIR sensor.
➨Microwave sensor has continuous field of detection zone where as PIR sensor has slotted detection zone. Hence PIR sensor may miss out objects. Hence microwave sensors are better in security applications compare to PIR sensors.
➨Microwave sensors have higher false alarm rate compare to PIR sensors.
➨Microwave sensors are slightly costlier compare to PIR sensors.
➨Microwave sensors consume more energy than PIR sensors. PIR sensors consume about 0.8 to 1.0 Watt electricity and microwave sensors consume about 1.1 to 1.5 Watt.
➨Microwave sensors are suitable for large area security applications where as PIR sensors are suitable for smaller and compact premises.
Also refer difference between active motion sensor and passive motion sensor>>.

Conclusion: The best results are achieved by installing both microwave sensor and PIR sensor to leverage advantages of both the sensors.

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