Also note that the radar beam is wider in one direction and the fundamental operation of
the radar is not affected by the mounting orientation. This fact may be used to either
widen or narrow the detection zone in the direction that matters.
For a wider horizontal detection zone, mount the radar with the wider beam in the
horizontal direction. For a narrower horizontal detection zone, mount the radar with the
narrower beam in the horizontal direction. Please consult the installation section later in
this document to determine beam width based on mounting orientation.
Important things to remember about radar detection zone:
1.
The radar beam does not end abruptly at the specified angle. Per convention, we
specify “half-power” beam angles where the power falls off to half the value from
the center of the beam. Thus it is possible for the radar to detect strong targets
outside of the oval derived from a trigonometric calculation based on the beam
angle.
2.
Every target has different microwave reflective characteristics. This is
characterized by the RCS and affects how much microwave energy the target
returns back to the radar. This is one of the most important factors in reliable
detection. Simple rules of thumb are:
a.
Vehicle side typically has larger cross section than vehicle front
b.
Vehicle rear typically has larger cross section than vehicle front
c.
Larger target is likely to have larger RCS, thus a truck will provide a
stronger return signal then a passenger car or a motorcycle.
d.
Metal targets have larger cross section than non-metallic targets (like
humans, animals, plastics etc.)
e.
Metal surfaces joined at a 90-degree angle create perfect reflector.
f.
Perfectly flat metal surface at an angle other then 90 degrees may reflect
the radar beam away and result in a weak target.
3.
In a side firing configuration as the vehicle passes in front of the radar, an incident
angle momentarily becomes 90º and results in a strong return signal. This effect
manifests in a somewhat narrower detection zone compared to what may be
expected from the beam geometry.
4.
Unlike in a Doppler radar, with FMCW radar there is always a fixed internal
design limit to the maximum detection range. No matter how strong the target is,
it will not be detected beyond this limit. The maximum detection range may be
found in the
specification
and is different for various modes of operation.
