AIS Antenna

[Rappey]

There was no way I was going to pay a crazy amount of money for a splitter to run an ais transceiver using a vhf Antenna that isn't best tuned for ais.
I bought a proper ais tuned antenna for less than £50 and mounted it at head high on the back stay. Get 15nm mile no problem. Got vessels from a mile away with no antenna at all !

 

[johnalison]

My aerial is so badly adapted and its function debased by a splitter that I can't usually detect ships from more than about forty five miles

 

[Hoolie]

I know your angst, though I was encouraged by receiving a contact from over 250 miles with our masthead/splitter arrangement. Freak conditions of course, but I'm much more concerned that our Class B transmissions get as wide an audience as possible

 

[Daverw]

There was no way I was going to pay a crazy amount of money for a splitter to run an ais transceiver using a vhf Antenna that isn't best tuned for ais.
I bought a proper ais tuned antenna for less than £50 and mounted it at head high on the back stay. Get 15nm mile no problem. Got vessels from a mile away with no antenna at all !

normal vhf is tuned just below mid band around channel 16, the rest of the band is not very far out anyway, if you put an analyser on either they are virtually identical,

 

[Rappey]

Vhf using a half wave antenna will be 0.96m . An ais antenna will be 0.925m so some 3.5cm shorter.
I remember the days when setting the swr on an antenna and just 1mm longer or shorter made quite a difference. I applied this logic to getting the correct antenna for ais.
Most vhf antennas come with rg58 which according to many articles is pretty poor for going up a yacht mast as it will lose 50% of signal due to the length required to reach the top of a mast.
The ais having its own antenna at the rear of the boat means the cable length is dramatically reduced and has saved paying £200+ for a ais transponder compatible splitter.