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?

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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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?

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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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

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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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

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.

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?

Some are...Most work only the low bands...I know many
hams who couldn't care less about dx. They only talk to
other regional "good ole boys"....
But saying that, comparing a G5RV at 50 ft, against a
dipole at 7 ft, is fairly silly. The NVIS qualities are more
due to height above ground per wavelength, than the
length of the antenna.
Overall, I think the idea of running low dipoles, or using
ground screens, and pseudo "reflectors" etc, are
generally a waste of time.. If I were working NVIS on 75m,
I'd prefer a dipole at 50ft over one at 7 ft. It will have lower
ground losses, and I'd be willing to bet the NVIS performance
would be just as good as the low antenna. But, the medium
range performance would be a good bit better. Also, you
can work dx also...I've worked dx on 75m, using a dipole
at 35 ft...It's no big deal really...Just finding the DX to talk to
is more difficult. Also...NVIS antennas are not low noise,
unless they are defective in some way...They may reduce
the reception of far off lightning, if that static arrives at
low angles.. A low dipole has great reception of noise...
Straight up....A low to medium height dipole already has
enough gain straight up. I don't really want to enhance it
further...I also want to have decent performance on longer
paths...Listen to all the BIG strappers on 75m...I bet very few
are running real low dipoles with screens...Most will be running
higher dipoles hung from towers, trees, etc...
MK

.... 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?