Microwave sensors are motion detection devices that flood a specific area with an electronic field. A movement in the area disturbs the field and generates an alarm. Microwave sensors are typically used for detection in long, flat, narrow perimeter zones.
They are classified as an active, visible, volumetric, freestanding, and line-of-sight sensor.
Microwave sensors transmit microwave signals in the “X” band. These signals are generated by a diode operating within specific limits that do not affect humans or the operation of pacemakers.
The effective detection zone width and height of a given microwave system will largely depend on the mounting height of the antennas when operating over the same type of surface at the same range. The mounting height is measured from the centre of the antenna aperture to the ground. When properly aligned, the maximum detection height and width will occur at mid-range. During installation in the field, antenna heights can be adjusted for maximum signal while monitoring the signal at the receiver. Most manufacturers indicate the linear operating range to be approximately 100–150 meters (328–492 feet) when detection of a stomach- crawling intruder is a requirement. Detection zone sizes are normally stated for mid-range between the transmitter and receiver at the maximum antenna separation.