These motion detectors emit microwave signals and measure the time taken for the signal to be reflected back to the sensor, this is known as the echo time. The echo time is used to calculate the distances from all the stationary objects in the detection zone, to establish a baseline to work from. A person moving into the detection zone causes a disruption in the microwave beam, changing the echo time and triggering the lights.


These sensors detect heat. They do this by measuring the ambient temperature of the room using several detection beams. When a difference in temperature is detected by one of the beams, the sensor is activated, switching on the lights. When all the beams sense the same temperature again, the lights will switch off.

A Comparison

When choosing the best sensor for your application, there are many aspects to take into account;

  PIR Microwave
Sensitivity Under sensitive in higher background temperatures.
Over sensitive in lower temperatures.
Consistent detection over all temperatures.
Coverage 90° 360°
Detection Can be insensitive when walking directly towards the sensor. Can sense movement through walls.

Tri-Sensor PIR

As mentioned above, a standard PIR operates differently at different temperatures, not triggering when it gets hotter but in the colder months triggering for every small, distant, movement.

To combat the PIRs temperature detection fault, Green Lighting developed a PIR sensor with Tri-Sensor Technology. The P-Lux LED Lantern Range, incorporates a sensor that combines a PIR with a thermometer, allowing the lantern to automatically adjust the PIRs sensitivity depending on the ambient temperature.

This, combined with a photocell and the Lux-Up, Lux-Down feature of the P-Lux, makes these lanterns some of the best on the market, functioning perfectly all year round.

Adjustable Microwave Sensors

To combat Microwaves Sensors tendency to be overly sensitive, we have developed a fitting that can be adjusted to suit your personal needs. This Microwave Ceiling Bulkhead has been manufactured so that it can detect movement from any angle from a distance of up to 6m, with a sensitivity which can be adjusted easily with the flick of a switch. This fitting also incorporates a photocell which, thanks to its easily customisable settings, can be altered to react to different light levels to fit its desired purpose. This fitting has been designed so it is only on when it needs to be, saving energy and, therefore, money for the end user.