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• Avoid having a rope or signal flag from winding around the radiating section
thereby preventing it from rotating.
• Avoid the effects of dust and heat caused by smoke from a chimney.
• When determining the appropriate antenna height and installation location,
take into consideration the reduction of vibration, the strength of the hull and
the antenna mount base, and maintenance properties.
• Provide for maintenance space: platform, safety link, hand rail, steps, etc.
The lower edge of a radar antenna should be a minimum of 500 mm above
any safety rail.
• When installing the antenna, select a location where there are the fewest
structural objects in the surrounding area so that the capability to drive the
motor will not be depressed by the non-equability wind which is likely to
rotate the antenna.
2) Electrical selection criteria
• The installation height of the antenna relates to the maximum detection
distance. The higher is the better. (However, if it is too high, radio wave
energy greatly attenuates above the antenna's vertical beam width (the
point -3dB from the peak of the main lobe). As a result, it is difficult to
detect a close-in target.
installation height by taking into consideration the weight, maximum length
of the cable, and maintenance after installation.
• If the installation height of the antenna is low, it is difficult to detect a long
distance target. The ship's mast, derrick, and construction objects interfere
with radiating beam causing the range that cannot be viewed on the radar
display to increase.
Generally, the lowest antenna installation position is supposed to be on the
A-B line shown in Fig.1-2. In the case of the radar antenna, 2θ equals 20°.
Specifically, the antenna position is normally elevated so that the building
etc do not interfere with radiating beam. The inside of A point might be blind
area due to antenna beam does not propagation. So, if near distance should
be covered, antenna installation position must be considered carefully.
θ = 10°
θ
Sea surface
A
Fig.1-2 Antenna installation height vs Vertical beam width
Sea clutter also increases.
L
Building etc.
Blind area
3
7ZPRR0001
Determine the
B
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