Kelvin Hughes Limited SXV-A1 Manuel D’Utilisation
SharpEye™ SCV & SxV X-Band Radome Radar
Chapter 4: Positioning of radar equipment
KH-1650-CA issue 1
Page 17 of 60
MULTIPATH INTERFERENCE
Radar energy reflects from the target directly or following reflection at the surface of the sea. The
result is that sometimes the two signals will reinforce each other while at other times they will cancel
and create a null.
In marine applications (SCV) Multipath is most pronounced when the sea is calm, acting like a mirror,
and when the target is simple (essentially comprising a single reflector) such as a buoy. Here
multipath reflection may produce a large number of signal nulls at short range. These become less
frequent as range increases.
In the higher sea states when the sea is rough and is less like a mirror or when the target is complex
(comprising a number of reflectors), as are many vessels, the effect of multipath is less pronounced
so that the nulls are less deep.
Land based installations can also suffer from multipath. The reflection characteristics can change
based on terrain, dampness etc.
As the height of the radar antenna (or target) increases, then the frequency of the nulls also
increases.
It is clear that there is no definitive solution to the installation of a radar antenna on a vessel or a
permanent land based site.
Each installation should be examined on its own merit with each aspect of performance assessed
appropriately. To this end, we advise that you seek guidance from Kelvin Hughes for antenna
installations by submitting a drawing illustrating the position of the antenna in relation to the vessel’s
structure (SCV) or mounting structure (SxV) and nearby obstacles.
ANTENNA LOCATION AND SEPARATION
SharpEye
TM
SCV and SxV radomes contain a SharpEye
TM
radar transceiver and a GNSS antenna.
The system must be mounted with a clear view of the horizon.
Wherever possible, ensure the antenna is placed outside the beam path of any other transmitting
equipment for example:
Radar:
Typically ±15° from the array’s centre point.
Satcom:
INMARSAT A, B, C, or M; typically ±10° from the array’s centre point in any
of the possible transmitting directions.
VHF/ SSB:
Do not place within 3 metres of a VHF or SSB radios or their antennas.
Image of
Target
Target