QK-AS02 VHF antenna on a fibre glass boat

Quark-elec AIS receiver and NMEA MUX products questions

QK-AS02 VHF antenna on a fibre glass boat

Postby Martin » Mon Apr 24, 2017 9:39 pm

I have a QK-A042 and a QK-AS02 VHF antenna. I have had big problems receiving AIS signals when the antenna is standing on a any materials except a magnetic metal plate. My problem is that my boat is made of fibreglass and the metal on board is not magnetic (stainless steel). Is it correct that this antenna does not work unless it is standing on a magnetic metal plate? Do you have a solution I can implement on board to get a good AIS signal reception with this antenna?
Martin
 
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Re: QK-AS02 VHF antenna on a fibre glass boat

Postby admin » Wed Apr 26, 2017 10:34 am

Hi Martin,
Generally, it should not make difference to your reception whether your antenna is standing on a metal plate, or not, however, the bases we supply are designed to be mounted on metal so I understand that with a fibreglass boat that could present a problem. Your reception issue is more likely to be caused by other factors. I have included a link to a very good article about antennae and their installation which may provide some useful pointers.

http://www.boat-project.com/tutorials/vhfant.htm

In the meantime please ensure the whip is not close to, or in contact with any metals, as that will definitely reduce your reception.
I hope that helps, if you continue to have a problem please let me know,
Kit
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Re: QK-AS02 VHF antenna on a fibre glass boat

Postby Martin » Sat Apr 29, 2017 3:35 pm

This type of antenna is, as you say, designed to be used on a metallic surface. It does not need to be a magnetic surface, but having a magnet foot and a magnetic surface is an easy way of mounting the antenna. I have tested with an aluminium plate.
It is a huge difference in having the antenna on a metallic surface or not. Have you tested this antenna with and without it standing on a metallic surface ie. having a ground plane?
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Re: QK-AS02 VHF antenna on a fibre glass boat

Postby g4emm » Mon Jun 05, 2017 12:04 pm

Use an antenna that is approximately a metre long - half wave antenna - these can work well because of their length without a ground plane hence they work up a mast!
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Re: QK-AS02 VHF antenna on a fibre glass boat

Postby Martin » Wed Aug 02, 2017 10:02 pm

What if you, Quark-Elec, could offer a simple J-Pole antenna? Having an inexpensive yet efficient antenna that can work without any ground plane and that can easily be carried around would be very useful.
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Re: QK-AS02 VHF antenna on a fibre glass boat

Postby Stenn » Wed Aug 09, 2017 2:51 am

Hi Martin.

I believe the issue of having a ground plane or not, i.e. your metalic base, is only relevant for transmitting, not receive-only....in a HAM setup, any random-length long-wire connected only to center pin, no ground, can be used for RX.....and VHF is such short wave-length, I'd be surprised ground-plane would be factor....

...but then you do seem to be proving there's an issue, by your own experiments/experience....
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Re: QK-AS02 VHF antenna on a fibre glass boat

Postby admin » Wed Aug 09, 2017 9:24 am

Hi Martin, we'll put J-Pole antenna on the wish list!
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