Maximum Radar Range; Factors Impairing A Radar Picture - Raymarine E120W Reference Manual

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Maximum radar range

Maximum radar range is essentially line-of-sight, so is limited by the height of the
scanner and the height of the target as illustrated below:
The table below shows typical maximum radar ranges for various radar antenna
heights and target heights. Remember that although the radar horizon is greater than
the optical horizon, the radar can only detect targets if a large enough target is above
the radar horizon.
Antenna height (m)

Factors impairing a radar picture

Not all radar echoes are produced by valid targets. Spurious echoes may be caused by:
• Side lobes.
• Indirect echoes.
• Multiple echoes.
• Blind sectors.
• Sea, rain or snow clutter.
• Interference.
Through observation, practice, and experience, you can generally detect these
conditions very quickly and use the radar controls to minimize them.
a
1
Radar
R max = 2.23 (
R max maximum radar range
h radar antenna height
H target height
R max = radar horizon of antenna (
Target height (m)
3
3
5
5
E-Series Networked Display Reference Manual
R max
a
2
Earth
h + H )
in nautical miles
in metres
in metres
a
) + radar horizon of target (
1
Maximum range (nm)
3
10
3
10
Cliff
a
)
2
7.7
10.9
8.8
12.0