JRC JMA-3300 Series, Installation Manual

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Chapter 2 INSTALLATION OF THE SCANNER
2.1 SELECTING THE INSTALLATION POSITION
2-2
Table 2.1-1 Swing circle
Scanner model (length) Swing circle
NKE-2042 620 mm (radome)
NKE-2043 620 mm (radome)
NKE-2062/HS (3.9 feet) 1,220 mm
NKE-2063/HS (3.9 feet) 1,220 mm
NKE-2103-4/4HS (4 feet) 1,320 mm
NKE-2103-6/6HS (6 feet) 1,910 mm
 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 scanner height and installation
location, take into consideration the reduction of vibration, the strength
of the hull and the scanner mount base, and maintenance properties.
 Provide for maintenance space: platform, safety link, hand rail, steps,
etc.

Electrical selection criteria
 The installation height of the scanner relates to the maximum detection distance. The
higher, the better. However, if it is too high, radio wave energy greatly attenuates
above the scanner's vertical beam width (the point -3 dB from the peak of the main
lobe). As a result, it is difficult to detect a close-in target. Sea clutter also increases.
Determine the installation height by taking into consideration the weight, maximum
length of the cable, and maintenance after installation. If the installation height of the
scanner is low, it is difficult to detect a long distance target. The ship's mast, derrick,
and chimney interfere with radiating beam causing the range that cannot be viewed
on the radar display to increase.
Generally, the lowest scanner installation position is supposed to be on the A-B line
shown in Fig. 2.1-1. In the case of the JMA-3300 type radar, 2

equals 20°.
Specifically, the scanner position is normally elevated so that the chimney and the
shrine-gate type mast do not interfere with radiating beam.