AJAX CombiProtect User Manual page 10

As a minimum, move the device even 20 cm shift can significantly improve the
quality of reception.
If after moving the device still has a low or unstable signal strength, use a
.
The direction of the detector lens should be perpendicular to the probable way
of intrusion into the room. The detector microphone should be positioned at the
angle of no more than 90 degrees relative to the window.
Make sure that any furniture, domestic plants, vases, decorative or glass
structures do not block the field of view of the detector.
We recommend installing the detector at the height of 2.4 meters.
If the detector is not installed at the recommended height, this will reduce the
area of the motion detection zone and impair the operation of the function of
ignoring animals.