vhf ariel. can I mount it next to 27mg arieal
Submitted by chookc on Sun, 2010-01-24 11:39
Guys ,
mounting a new arieal and radio (VHF to the boat) can I mount the 2nd arial for the vhf beside the 27mg arial... Notice on most boats they are on eitherside of the cab. My current arieal is mounted on a plate at rear of hard top roof in the centre. Would only be about 200mm between the arieals.
Cheers
Craig.
Faulkner Family
Posts: 18055
Date Joined: 11/03/08
from memory with what i have
from memory with what i have been told, further away thye better. no interfeerance
RUSS and SANDY. A family that fishes together stays together
iana
Posts: 652
Date Joined: 21/09/09
Mount them as far apart as possible.
What you see is what you should do, mount them one on each side of the boat, otherwise the aerials will induce power into each other.
I did away with the 27 meg altogether, coupled the VHF to my GPS so I could use the emergency red button.
sunshine
Posts: 2623
Date Joined: 03/03/09
Proximity effect
Causes a null in the direction of the other antenna rather than being omnidirectional (bit like cutting a segment out of an orange with the missing bit totally blanked to any signal either receive or send)
(Ex-ham radio operator and was the owner of the largest quad array in WA)
Blacky
Posts: 17
Date Joined: 20/02/10
potentially one antenna can
potentially one antenna can act as a reflector and or director for the other, depending on antenna lengths. Rx wont be an issue, however Tx might. if 20cm is all you have to work with then it will be ok, i would be willings to gamble that you wont even be able to tell the difference.
sunshine
Posts: 2623
Date Joined: 03/03/09
Phased verticals can do that
As can verticals slightly longer or shorter in wavelength but here we are talking about totally different frequencies miles apart. Unless I have forgotten all of my antenna theory (and I had some of the largest arrays in Perth all of which were built by hand not purchased retail) the further apart the better - if you can borrow a decent SWR metre you can actually watch the effects of proximity just but moving an antenna closer whilst transmitting on cw