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Old June 11th 05, 07:39 AM
William Taylor
 
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Default Interesting Cloud Burner Antenna

http://www.hamuniverse.com/supernvis.html

The claim is that a dipole 7 feet off the ground has
a 10db gain over a G5RV at 50 feet.

Is that possible, or hype?


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Old June 11th 05, 02:53 PM
Cecil Moore
 
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William Taylor wrote:

http://www.hamuniverse.com/supernvis.html

The claim is that a dipole 7 feet off the ground has
a 10db gain over a G5RV at 50 feet.

Is that possible, or hype?


It's could be true for 30m or 10m. Certainly not true
for the bands for which the G5RV was originally
intended namely 80m, 40m, and 20m. 12m comes as a
bonus.

You can make a G5RV just about as good as a dipole
on all HF bands.
0'-16' 20'
xmtr---coax---+---LLLS---+---450 ohm LL---+-102' dipole

The key is the LLLS, ladder-line length selector that
allows selection of 0'-16' in increments of one foot.
It requires four 4PDT relays, like the Omron LY4.
The relays are controlled from the operating position
but auto-switching would be easy to implement with a
directional coupler and a couple of op-amps. The
largest loop of ladder-line is only 2.5' in diameter.
--
73, Cecil http://www.qsl.net/w5dxp

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Old June 11th 05, 02:59 PM
Fred W4JLE
 
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Anecdotal evidence. First note he says 160 meter G5RV, one could assume he
has doubled the size to 204 feet to meet this claim. Run a 204 foot dipole
through EZNEC on 40 and you can see why the claims may be valid in some
directions.

"William Taylor" wrote in message
...
http://www.hamuniverse.com/supernvis.html

The claim is that a dipole 7 feet off the ground has
a 10db gain over a G5RV at 50 feet.

Is that possible, or hype?



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Old June 11th 05, 03:26 PM
Cecil Moore
 
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Fred W4JLE wrote:

Anecdotal evidence. First note he says 160 meter G5RV, one could assume he
has doubled the size to 204 feet to meet this claim. Run a 204 foot dipole
through EZNEC on 40 and you can see why the claims may be valid in some
directions.


I didn't look at it but just noticed 'nvis' in the title.
Of course, a dipole at 7 feet will have near-vertical gain
over a G5RV at 50 feet. Near-vertical gain is NOT what the
majority of hams desire. Near-vertical gain is the antithesis
of DX.

"William Taylor" wrote in message
...

http://www.hamuniverse.com/supernvis.html

The claim is that a dipole 7 feet off the ground has
a 10db gain over a G5RV at 50 feet.

Is that possible, or hype?


--
73, Cecil http://www.qsl.net/w5dxp

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Old June 11th 05, 08:24 PM
Ed
 
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I didn't look at it but just noticed 'nvis' in the title.
Of course, a dipole at 7 feet will have near-vertical gain
over a G5RV at 50 feet. Near-vertical gain is NOT what the
majority of hams desire. Near-vertical gain is the antithesis
of DX.



I differ on that opinion. My 40M/80M operational preferences are
definitely for close-in communications, such as getting on the Noon-Time
net, various in-state 75M nets, and other "local" activities". The lower
noise factor of the NVIS antenna helps, too. Of course, its best to have
two antennas, one such as NVIS and another well placed dipole, for optimum
choice.


Ed K7AAT


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Old June 11th 05, 08:33 PM
John Smith
 
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.... personally, I apply a little sticker of an arrow on each antenna I
build...

.... hey it can't hurt!!! grin

John

"William Taylor" wrote in message
...
http://www.hamuniverse.com/supernvis.html

The claim is that a dipole 7 feet off the ground has
a 10db gain over a G5RV at 50 feet.

Is that possible, or hype?



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Old June 11th 05, 09:00 PM
Cecil Moore
 
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Ed wrote:

I didn't look at it but just noticed 'nvis' in the title.
Of course, a dipole at 7 feet will have near-vertical gain
over a G5RV at 50 feet. Near-vertical gain is NOT what the
majority of hams desire. Near-vertical gain is the antithesis
of DX.


I differ on that opinion. My 40M/80M operational preferences are
definitely for close-in communications, such as getting on the Noon-Time
net, various in-state 75M nets, and other "local" activities". The lower
noise factor of the NVIS antenna helps, too. Of course, its best to have
two antennas, one such as NVIS and another well placed dipole, for optimum
choice.


What are you disagreeing with? How much DX do you work with
your NVIS antenna? Do you really think the majority of hams
are only interested in local communications on HF?
--
73, Cecil http://www.qsl.net/w5dxp

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Old June 11th 05, 09:25 PM
Ed
 
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What are you disagreeing with? How much DX do you work with
your NVIS antenna? Do you really think the majority of hams
are only interested in local communications on HF?


I guess my disagreement was with the word "majority"... but then, I was
thinking of 75M/40M and not the higher bands. I would say on the two bands
I meant to restrict my comments too, that more hams probably do communicate
"locally" rather than hunt DX.


Ed

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Old June 12th 05, 02:25 AM
Terry O'Neill
 
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I used an antenna quite similar to this (mine had only one ground reflector)
for local (within 300 miles) 40 meter ssb. Mine was at about 16' high.
About 1/8 wl on 40. It was consistently 2-3 s units better than the the high
(70') 40 meter dipole when working stations within about 300 miles. 300-1000
miles they were very close. For DX the high dipole was always better.

Here's a good web site that explains the phenomema

http://www.athensarc.org/nvis.htm




"William Taylor" wrote in message
...
http://www.hamuniverse.com/supernvis.html

The claim is that a dipole 7 feet off the ground has
a 10db gain over a G5RV at 50 feet.

Is that possible, or hype?



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Old June 12th 05, 03:17 PM
Korbin Dallas
 
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On Sat, 11 Jun 2005 15:00:18 -0500, Cecil Moore wrote:

Ed wrote:

I didn't look at it but just noticed 'nvis' in the title.
Of course, a dipole at 7 feet will have near-vertical gain
over a G5RV at 50 feet. Near-vertical gain is NOT what the
majority of hams desire. Near-vertical gain is the antithesis
of DX.


I differ on that opinion. My 40M/80M operational preferences are
definitely for close-in communications, such as getting on the Noon-Time
net, various in-state 75M nets, and other "local" activities". The lower
noise factor of the NVIS antenna helps, too. Of course, its best to have
two antennas, one such as NVIS and another well placed dipole, for optimum
choice.


What are you disagreeing with? How much DX do you work with
your NVIS antenna? Do you really think the majority of hams
are only interested in local communications on HF?


Yes the majority of hams are indeed interested in Local HF communications
on 80 & 40. Something that will reliably commutate out to 300-400
miles.

When they think of DX they think 20 - 10 meters.

Those that are interested in DX on 80 meters are a very small minority.


--
Korbin Dallas
The name was changed to protect the guilty.



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