Know anywhere I can find ratings to help decide which antenna?? I have a 23
foot center console. Generally range 10-15 miles offshore and plan to mount
the antenna on my

On Mon, 29 Dec 2003 03:00:38 GMT, "sk" wrote:

Know anywhere I can find ratings to help decide which antenna?? I have a 23
foot center console. Generally range 10-15 miles offshore and plan to mount
the antenna on my


I don't recommend the very high gain fiberglass antennas for VHF on
small boats that roll so much in swell.

High gain antennas get their high gain from squeezing the vertical
antenna's donut-shaped radiation pattern into one that looks like you
stepped on the donut. As long as the antenna is vertical, this is
fine and steps up the gain very nicely. But, as the antenna is TILTED
in any direction, this flattened-out pattern also tilts,
simultaneously, radiating all that power into the sea on one side and
into the clouds on the other, putting the receiving station in an area
of its radiation pattern that is more of a null, than it would be if
you had used a simpler 1/2 wave vertical whip with the fat donut
pattern. The effect on the signal at the receiver when the super
antenna is rolling around is a signal that's fading in and out as the
high gain pattern plays over the receiving station on its way to
skyward or seaward as the boat rolls.

The best small boat antenna is an end-fed, half wave as high up as you
can mount it. I've used Metz antennas since they started making
home-brew ham antennas in the 70's. Metz antennas have a no-nonsense
LIFETIME warranty! Who could ask for more?
http://www.metzcommunication.com/
I think the Manta 6 is the finest small boat antenna made.
http://www.metzcommunication.com/manta6.htm
It is a simple 1/2 wave, no ground plane, end-fed VHF antenna and will
work anywhere you can put it, plastic, metal, ground or not. The
connector on the bottom of it is the standard SO-239 "CB" connector.
If you break the coil, they'll send you a new one. The whip is fine
stainless steel and the only way you can break it is by FORCE. I have
LOST a couple of them overboard over the years when the little clamp
on top of the coil wasn't tight, though.....

Shakespeare also makes an end-fed halfwave, but it sucks because the
COAX IS PERMANENTLY MOUNTED IN IT so you can't FIX IT when it breaks!
You also can't simply replace a lost whip with a piece of coat hangar
wire, like you can on the Metz, out in the boondocks to get the radio
working again......

Metz has lots of different crazy mounts for it.....

Larry: please define "very high gain"? 9db? 6db?

FWiW, I have have a 6db 8' Shake Galaxy on my 17' whaler. Works fine
even when it's rock and roll.

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Larry W4CSC" wrote in message ...
On Mon, 29 Dec 2003 03:00:38 GMT, "sk" wrote:

Know anywhere I can find ratings to help decide which antenna?? I have a 23
foot center console. Generally range 10-15 miles offshore and plan to mount
the antenna on my


I don't recommend the very high gain fiberglass antennas for VHF on
small boats that roll so much in swell.

High gain antennas get their high gain from squeezing the vertical
antenna's donut-shaped radiation pattern into one that looks like you
stepped on the donut. As long as the antenna is vertical, this is
fine and steps up the gain very nicely. But, as the antenna is TILTED
in any direction, this flattened-out pattern also tilts,
simultaneously, radiating all that power into the sea on one side and
into the clouds on the other, putting the receiving station in an area
of its radiation pattern that is more of a null, than it would be if
you had used a simpler 1/2 wave vertical whip with the fat donut
pattern. The effect on the signal at the receiver when the super
antenna is rolling around is a signal that's fading in and out as the
high gain pattern plays over the receiving station on its way to
skyward or seaward as the boat rolls.

The best small boat antenna is an end-fed, half wave as high up as you
can mount it. I've used Metz antennas since they started making
home-brew ham antennas in the 70's. Metz antennas have a no-nonsense
LIFETIME warranty! Who could ask for more?
http://www.metzcommunication.com/
I think the Manta 6 is the finest small boat antenna made.
http://www.metzcommunication.com/manta6.htm
It is a simple 1/2 wave, no ground plane, end-fed VHF antenna and will
work anywhere you can put it, plastic, metal, ground or not. The
connector on the bottom of it is the standard SO-239 "CB" connector.
If you break the coil, they'll send you a new one. The whip is fine
stainless steel and the only way you can break it is by FORCE. I have
LOST a couple of them overboard over the years when the little clamp
on top of the coil wasn't tight, though.....

Shakespeare also makes an end-fed halfwave, but it sucks because the
COAX IS PERMANENTLY MOUNTED IN IT so you can't FIX IT when it breaks!
You also can't simply replace a lost whip with a piece of coat hangar
wire, like you can on the Metz, out in the boondocks to get the radio
working again......

Metz has lots of different crazy mounts for it.....

Chuck Tribolet wrote:

Larry: please define "very high gain"? 9db? 6db?

FWiW, I have have a 6db 8' Shake Galaxy on my 17' whaler. Works fine
even when it's rock and roll.


I have an 8' "Digital" brand antenna hooked up to my VHF on my 25'
Parker pilothouse. Works fine in the rock and roll of the Atlantic Ocean.

Visit the boat at:

http://photos.yahoo.com/hakrause



--
Email sent to is never read.

On Sun, 28 Dec 2003 21:49:17 -0800, "Chuck Tribolet"
wrote:

Larry: please define "very high gain"? 9db? 6db?

The higher the "gain" of the antenna, the flatter and less "thick" its
radiation pattern. The 9db antenna has a much flatter radiation
pattern than the 6db.

FWiW, I have have a 6db 8' Shake Galaxy on my 17' whaler. Works fine
even when it's rock and roll.

"In range" you'll really not see the difference on FM, which signal
strength has less effect on until it's near the fringe.

I just don't like the big, long fiberglass whips on small boats.
Neither does USCG. They got fed up with them breaking off and all use
the Metz, now. Metz brags about it on their webpage.

If jumping waves with the SeaRayder jetboat can't break it, your boat
won't, either. Mine is even mounted way up in the bow and has
survived even submarining the bow at speed.....drowning us all in the
process...(c;

A fiberglass tube filled with hookup wire antenna elements would never
make it....hee hee.

On Tue, 30 Dec 2003 04:01:15 GMT, (Larry W4CSC) wrote:

On Sun, 28 Dec 2003 21:49:17 -0800, "Chuck Tribolet"
wrote:

Larry: please define "very high gain"? 9db? 6db?

The higher the "gain" of the antenna, the flatter and less "thick" its
radiation pattern. The 9db antenna has a much flatter radiation
pattern than the 6db.

So, how does the horizon work into the gain equation?

FWiW, I have have a 6db 8' Shake Galaxy on my 17' whaler. Works fine
even when it's rock and roll.

"In range" you'll really not see the difference on FM, which signal
strength has less effect on until it's near the fringe.

I just don't like the big, long fiberglass whips on small boats.
Neither does USCG. They got fed up with them breaking off and all use
the Metz, now. Metz brags about it on their webpage.

Interesting - all the USCG small boats around these parts use the
Shakespeare 396-1 which is a center-fed 1/2 wave.

I use one and it's been great antenna.

Later,

Tom
S. Woodstock, CT
----------
"I object to fishing tournaments less for
what they do to fish than what they do to
fishermen." Ted Williams - 1964

On Wed, 31 Dec 2003 11:30:07 GMT, Jack Burton
wrote:

On Tue, 30 Dec 2003 04:01:15 GMT, (Larry W4CSC) wrote:

On Sun, 28 Dec 2003 21:49:17 -0800, "Chuck Tribolet"
wrote:

Larry: please define "very high gain"? 9db? 6db?

The higher the "gain" of the antenna, the flatter and less "thick" its
radiation pattern. The 9db antenna has a much flatter radiation
pattern than the 6db.

So, how does the horizon work into the gain equation?

Picture the vertical antenna standing vertically. It's a high-gain
fiberglass type with many phased elements imbedded into it. Its
radiation pattern is perpendicular to the antenna in a flattened donut
shape. When you step on a donut, its outer edge moves outward as its
thickness is squeezed. That's exactly what's happening to get more
radiation to the horizon where the receiving station is located. The
phased array squeezes the fat round donut of the 1/2 wave, which
bulges out in the middle making a bigger signal perpendicular to the
antenna. This pattern moves with the antenna, always perpendicular to
it.

Now, tilt the antenna towards the receiving station. (Boat pitched?)
The flattened donut is now pointing into the water on the side towards
the receiving station. The signal level at the receiving station
drops, drastically, because this pattern is so flattened. On an FM
receiver, you hear no difference in signal "loudness" as signal
varies, UNTIL that signal drops below the receiver's noise floor,
usually a few hundredths of a microvolt, at which point the receiver
"hiss" of its FM detector gets louder and louder. As the signal
increases, again, the FM receiver "quiets", the hissing drops. This
is the only time the effect of the high gain antenna's flattened
pattern will cause communications problems. If the antenna's received
signal drops from 800 uV to 40 uV, you won't notice it. 40 uV will
keep the receiver hiss quiet. But, if we are talking about adding
this pattern tilting effect to the boat riding down into the trough of
those 30' rollers in a "worst case scenario" where it really counts,
THEN we are talking about disrupted comms. The best antenna for this
situation is NOT the 9dB fiberglass beast mounted on the side of the
helm console.....but the 1/2 wave Metz stainless whip mounted as high
up as you can get it.....with its fat pattern less effected by tilting
that's still sticking up above the waves on top of the sailboat
mast....like a beacon from the lighthouse.


FWiW, I have have a 6db 8' Shake Galaxy on my 17' whaler. Works fine
even when it's rock and roll.

"In range" you'll really not see the difference on FM, which signal
strength has less effect on until it's near the fringe.

I just don't like the big, long fiberglass whips on small boats.
Neither does USCG. They got fed up with them breaking off and all use
the Metz, now. Metz brags about it on their webpage.

Interesting - all the USCG small boats around these parts use the
Shakespeare 396-1 which is a center-fed 1/2 wave.

I use one and it's been great antenna.

That's the best antenna mounted as high as you can get it. It's
end-fed by a transformer in that cylinder base. It requires no
groundplane. I just don't like the way I can't replace the broken
cable permanently mounted to it up inside.....or the screwed-on whip
because I can't slip a 34" piece of coat hanger into the end when the
whip gets busted off by that little pitchpole we did sideways to that
Perfect Strom roller in the night. The Metz whip is mounted in a
gripping ferrule. Coat hanger wire slips right in where the broken
whip comes out.