Virtual Image; Shadow Sector - Furuno FR-8062 Operator's Manual

2. RADAR OBSERVATION
2.2.3

Virtual image

A relatively large target close to your ship may be represented at two positions on the screen. One
of them is the true echo directly reflected by the target and the other is a false echo which is
caused by the mirror effect of a large object on or close to your ship as shown in the figure below.
If your ship comes close to a large metal bridge, for example, such a false echo may temporarily
be seen on the screen.
2.2.4

Shadow sector

Funnels, stacks, masts, or derricks in the path of the antenna block the radar beam. If the angle
subtended at the antenna is more than a few degrees, a non-detecting sector may be produced.
Within this sector targets can not be detected.
2-4
Target ship
Own ship
True
echo
Mirror image
of target ship
Virtual image
Radar
mast
Shadow sector
Shadow sectors
False
echo
Radar
antenna