1. HOW TO INSTALL THE SYSTEM
1-7
1.5 Antenna
The antenna plays the most important role in radio communication. If it cannot receive
or transmit due to improper installation, even the most sophisticated transceiver will
be useless. After setting up the equipment, confirm that the antenna can tune all fre-
quencies.
Types of antennas
• The most commonly used antenna is a whip antenna. The recommended minimum
total length is 10 meters. For an 8 m whip antenna, secure it with a lead-in wire of
at least 2 m in length, as shown in the illustration below.
• A long wire antenna can also be used. The total length must be between 10 and 18
meters.
General requirements
• Separate the TX antenna as far as possible from stays, metallic objects, and direc-
tion finder antenna.
• The distance to an Inmarsat antenna must be more than five meters.
• The RX antenna (required for duplex communications) should be separated at least
five meters from the TX antenna.
• Use a wave-type insulator to connect to the coupler (or antenna switch) and leave
some slack in the feed-in wire, to prevent direct stress to the coupler.
• Install a antenna junction box (AJB1-1A) or matching box (ARD-1) at the base of the
antenna.
• Locate the insulator away from funnels, etc.
• The length of the vertical portion should be longer than four meters. Run as vertical-
ly as possible and within 10 degrees toward the vertical plane.
• See section 2.1.2 to connect the antenna wire with the ANT terminal of the antenna
coupler (or automatic antenna switch).
• Keep in mind antenna bending by wind and install away from any conductor.
8 m or
more
2 m or more
(when using an 8 m
whip antenna)
Automatic Antenna Switch
(option)
Antenna
Coupler
Pedestal
φ: Run the lead-in wire as vertically as possible.
In the COSAR Circ.32, it is recommended that
the lead-in wire should be more than 45 degrees
towards the horizontal plane.
φ
Insulator
Use a shackle.
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