MDC-2200/2500 Series Chapter 6 Principle of radar system
0093125002-02 6-3
Radar shadow
Since radar radio wave is line of sight in nature your stack mast close to the antenna or, a large ship or
mountain can create blind spots for which the radar cannot penetrate.. In such cases, they may
completely or partially hide targets and cast a long shadow.
Since the shadow your stack or mast is known at the time of installation, proper selection of the
antenna location is necessary to reduce the shadow effect. Since targets less likely to be seen in this
shadow area than in open sea, extra attention should used in shadowed areas.
False image
An image that does not actually exist (false image) at sea may appear on the display.
The phenomena that causes false echoes are categorized and be described as follows:
● False image
The image of large physical object in a close proximity may appear in two different orientations. One is
a real image and the other is a false image caused by wave re-reflected on the stack or the mast, etc.
On the display, one image appears with a right distance and bearing, and another one appears in the
direction of a stack, a mast, etc. These images may also be generate by being re-reflected from
bridges and quays too.
Passage of direct
reflection
Passage o
secondary
reflection
Mast, etc
Direction of false image
3
1
HU
Real image
False image
Figure 7-5 False image by virtual image
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