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Chapter 5. Screen view
5.1. The distance from the target to the height of target
The longest distance observable to the target is depending on the height of target, the distance to the
target and the height of antenna other than the matter of performance like Tx power, Antenna beam width
and receiving sensitivity. Radar signal is linear nature that is not affected by a round earth.
RADAR
TARGET
EARTH
A1
A2
A1 = 2.23√H1
A2 = 2.23√H2
A1+A2 = 2.23(√H1+√H2)
A1, A2 : [NM]
H1, H2 : [m]
H2
H1
For example, when the height of antenna is 3 meters above sea level, the ECHO image of island of 10
meters’ height and 10 miles away from the antenna can be displayed on Screen but the 5 meter’s height
with same distance is not displayed on screen since Radar signal transmitted does not reach.
But, these are of theoretical value and would not be constant due to environmental condition. In theory, the
target 10 miles away from the antenna requires 7.6 meters’ height, if it is lower than 7.6 meter, ECHO image
would not appear for which you must keep in mind.
10m
5m
3m
10NM
10NM
화면에 표시 되지 않는 섬
5.2. Reflection from the target
The strength of reflection from the target is related to not only the size of the target but the shape of the
materials composed of it, therefore the strength of reflection is not considered to be relative to the size of
the target.
Especially it is dependant to the geographical condition in coastal line. If the coastal line is flat slide, the
only mountain summit is displayed on the screen as an image, you should pay attention to the calculation of
distance upto the coastal line.
The ECHO reflected from flat land is so weak that it is unlikely to observe such land.
산
해안선
산
해안선
Coastal line
Mountain
The island, which is not displayed on Screen
Coastal line
Mountain
