3.2 Antenna
The antenna for the radio is fitted to the unit via a robust screw fitting to an M6 threaded socket
on the top of the radio. This system is more rugged than a traditional BNC connector, so the
radio’s drop-proof integrity is not compromised by the antenna fixing.
While the radio is drop-proof and very robust, damage to the antenna such as bending or kink-
ing may adversely affect the transmission efficiency of the unit, which may lead to overloading
of the power module. Damaged antennae should be replaced immediately.
Replacement antennae can be purchased from authorised Simrad Service Agents. Please refer to
section 3.7 for more details on spare parts and accessories available.
3.3 Transmission Range
Because VHF signals travel in a straight line and are not reflected back off the ionosphere as
lower frequency signals are, the range of VHF signals is limited to ‘line of sight’, beyond which
the other vessel passes behind the curve of the Earth. Therefore, the range will increase greatly
the higher above sea level the antenna is, as Fig 3.1 illustrates (assuming maximum transmis-
sion power is used):
Therefore, the typical range of a handheld radio such as this one used at sea level will be
approximately 8 Km (5 Miles). This will increase as height above sea level increases, or if the
other radio user’s antenna is at a greater height - note that the range between the yacht with the
antenna mounted on a 9 M (30 Ft) mast and the handheld user increases to 13-16 Km (8-10
Miles).
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