EN
AIS / VHF Antenna
10
AIS / VHF Antenna
Required
The Cortex Hub shares one antenna for both AIS and VHF functions.
A dedicated VHF antenna is required.
Choose a high quality omni-directional VHF antenna designed for the marine band
(156-162MHz) and ensure it is well tuned at the AIS end of the band (VSWR 2:1 or
less at 162MHz).
See Part Number VA159 (AIS/VHF Antenna).
Mount the antenna vertically, as high as possible (at least 2-3 meters (6-10 ft)
above the waterline). It is not recommended to place the VHF antenna near a mast
or other metal structures
Install the antenna a minimum of 3m (10ft) from any other VHF or HF antennas and
not within the beam path of a radar. Inadequate separation may damage the Cortex
transponder and void your warranty.
Never operate the Cortex Hub unless it is connected directly to a suitable VHF
antenna.
The VHF indicator light will display red when a problem is detected with the antenna
system (ie, the VSWR is above the acceptable level).
What does VSWR mean?
VSWR stands for Voltage Standing Wave Ratio and is a measure of the how well
matched a transmission line (e.g. the antenna cable connected to the VHF output of
your the Cortex Hub) is to its termination impedance (e.g. your antenna).
VSWR can be thought of as a comparative measure of how much power, generated
from your Cortex Hub AIS transponder, is delivered to the antenna and how much of
it is reflected back and lost in the poorly matched transmission line.
A high VSWR will reduce your effective transmission range and may also lead to
other problems.
