The MDU must be mounted firmly as movement relative to a fixed object within the coverage pattern will provide a Doppler output which could be detected as an intruder. Four mounting holes are provided in the corners of the MDU, which should be used to attach the unit firmly to the sensor. There should be no obstruction in front of the unit or within a 45° arc from the edges of the unit closer than 6mm from the face. Beyond this distance a plastic (ABS, polyethylene, PVC etc.) window can be mounted, through which the microwave signal will be transmitted. The thickness of this window will affect the sensitivity of the unit, although for the plastics mentioned above a 2mm thick window would be expected to reduce range by less than 10%.
The length of leads connecting the MDU to the signal processing circuitry must be minimised, to reduce pick up of electromagnetic interference. A maximum lead length of 1.5cm is recommended and screened leads are preferred. The housing of the unit can be grounded, but the electrical ground connection must be made through the GND tab. The unit is susceptible to static damage, so normal static handling procedures must be adopted when connecting or testing the units. In general, susceptibility to static damage is much reduced once the MDU is connected to the rest of the electronics.
Basic outline drawings for each are included on the relevant data sheet or can be downloaded here .