Pinnacle
Well-Known Member
Can't argue with that conclusion.
AIS Antenna Height
- Thread starter Tex
- Start date
Can't argue with that conclusion.
GHA
Well-Known Member
William_H
Well-Known Member
Refering to the backstay mounted AIS antenna. Certainly do not put it in a tube clamped to the wire. The described mount is excellent. The greater the spacing of the base away from the wire the better. There are obviously problems spacing it too far away. (mount rigidity) I would suggest however rather than have the antenna vertical that 20 degrees or so of away from vertical and away from the wire would be beneficial. This is just intuition mind you. But how many people use HHVHF with antenna off vertical. Ther is a huge loss with different polarisations ie one antenna vertical one horizontal but I think slight mis match has much less loss. However proximity to the wire will be theoretically really bad. olewill
Ric
Well-Known Member
I have had for the past year a separate AIS antenna mounted under the deck at the rear of a cockpit locker. It doesn't perform well there at all, so I am going to connect it to my masthead VHF antenna via a splitter. I have previously tried connecting the AIS directly to the masthead antenna, and the difference in performance is astonishing - I can see ships up to a 100 miles away, and shore coastguard stations even as far as 500 miles. I like the idea that with a quality low-loss splitter I will be able to see anybody within hailing distance.
BrianH
Well-Known Member
I wonder why you wish to receive target data from ships 100 miles away. AIS is a safety feature for close proximity vessels with the essential data being CPA and TCPA from them. It is my contention that anything beyond the earth's curvature at deck level is irrelevant to the principle and certainly not worth the added cost and inefficiency of a VHF splitter.
A separate, lower-mounted antenna also makes an emergency VHF antenna if the masthead one develops a problem or the mast itself goes over the side.
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Ric
Well-Known Member
Well I plan to keep the separate low mounted AIS antenna anyway to use as an emergency VHF antenna.
However, what interests me about being able to see anybody in hailing distance is that when well offshore I can immediately see any ships or coastguard stations that are in hailing range. Might make a big difference one day if I can identify anybody who might be ignoring my request for assistance.
However, what interests me about being able to see anybody in hailing distance is that when well offshore I can immediately see any ships or coastguard stations that are in hailing range. Might make a big difference one day if I can identify anybody who might be ignoring my request for assistance.
