VHF antenna height question
 

Need to install a new VHF antenna to a sailboat. Masthead would give
max antenna height, but drawback would be longer cable and extra
connectors. Have some experience about cable and connector losses
being a ham radio operator, and therefore give serious thought to
putting the antenna to top a a short pole on deck. Shorter cable, no
need for extra connectors as this would be permanent installation.
Plus much easier to install.

Lower antenna height (some 3-4 meters instead of 14m in masthead
installations) will of course reduce range, but would it stll be ok
for costal waters. In my home waters some 20 NM range is quit enough
to contact coastguard or SAR if needed.

Mika

Mika wrote:
Need to install a new VHF antenna to a sailboat. Masthead would give
max antenna height, but drawback would be longer cable and extra
connectors. Have some experience about cable and connector losses
being a ham radio operator, and therefore give serious thought to
putting the antenna to top a a short pole on deck. Shorter cable, no
need for extra connectors as this would be permanent installation.
Plus much easier to install.

Lower antenna height (some 3-4 meters instead of 14m in masthead
installations) will of course reduce range, but would it stll be ok
for costal waters. In my home waters some 20 NM range is quit enough
to contact coastguard or SAR if needed.

Mika

The "line of sight" at 3 metres would be about 7-8 miles. Is that enough?

Larry wrote:
( Mika) wrote in :

Need to install a new VHF antenna to a sailboat.

Put a 1/2 wave antenna as high as you can get it. 2000 meters is
great! but the top of the tallest mast will do just fine.

When you're screaming for help in a sinking boat, you can never have
an antenna that's too high! The altitude of the mast antenna more
than makes up for the length of the cabling losses. With a 25W Icom
and 1/2 wavelength Metz whip at 55 ft on the other end of 30 meters
of RG-58/U coax, Lionheart can call the US Coast Guard station way
out of sight of land.

Couldn't agree more!

Dennis.

RG-8 to the masthead is pretty much a standard rig for masthead antennas and
if the connectors are well done the signal loss is acceptable. The benefit
of the additional height far and away overrides any signal loss. Try to make
the antenna cable in a single run from the masthead to the back of the
radio - no through-deck connectors.

If you don't want to run cable of that diameter, don't try for the masthead
because the loss in the smaller cable over a run of that length would be
pretty bad.

Tom Dacon

" Mika" wrote in message
...

Need to install a new VHF antenna to a sailboat. Masthead would give
max antenna height, but drawback would be longer cable and extra
connectors. Have some experience about cable and connector losses
being a ham radio operator, and therefore give serious thought to
putting the antenna to top a a short pole on deck. Shorter cable, no
need for extra connectors as this would be permanent installation.
Plus much easier to install.

Lower antenna height (some 3-4 meters instead of 14m in masthead
installations) will of course reduce range, but would it stll be ok
for costal waters. In my home waters some 20 NM range is quit enough
to contact coastguard or SAR if needed.

Mika

On Tue, 16 Aug 2005 13:47:27 -0400, Larry wrote:

( Mika) wrote in :

Need to install a new VHF antenna to a sailboat.

Put a 1/2 wave antenna as high as you can get it. 2000 meters is great!
but the top of the tallest mast will do just fine.

When you're screaming for help in a sinking boat, you can never have an
antenna that's too high! The altitude of the mast antenna more than makes
up for the length of the cabling losses. With a 25W Icom and 1/2
wavelength Metz whip at 55 ft on the other end of 30 meters of RG-58/U
coax, Lionheart can call the US Coast Guard station way out of sight of
land.


but never, never, never ever use rg 58 cable. it's not shielded
properly. it has high loss.
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On Tue, 16 Aug 2005 14:57:34 -0700, "Tom Dacon"
wrote:

RG-8 to the masthead is pretty much a standard rig for masthead antennas and
if the connectors are well done the signal loss is acceptable. The benefit
of the additional height far and away overrides any signal loss. Try to make
the antenna cable in a single run from the masthead to the back of the
radio - no through-deck connectors.

If you don't want to run cable of that diameter, don't try for the masthead
because the loss in the smaller cable over a run of that length would be
pretty bad.


agreed. some folks have recommended rg 58 which has all the bad
characteristics and none of the good ones of proper coax.

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and enter 'wf3h' in the field

I have just seen a range of low-loss thin ad flexible 50 ohm coax -
aircell 7, ecoflex 10, ecoflex 15. If its as good as it claims to be,
i would be great for use on boats for both HF and VHF. Has anyone used
it?