RadioBanter

RadioBanter (https://www.radiobanter.com/)
-   Antenna (https://www.radiobanter.com/antenna/)
-   -   Vertical on a tower (https://www.radiobanter.com/antenna/86911-vertical-tower.html)

Roy Lewallen January 24th 06 08:52 PM

Vertical on a tower
 
wrote:

It's not a fair comparison
since the vertical was given a 2x height advantage. (That's
like putting my three foot six inch grandson up against
Shaquelle O'Neal in basketball. :-) Put the dipole at 70
feet, like the vertical was, and see what happens.

I mounted both as high as they would go. I don't consider
the GP as having quite twice the height advantage due to
the current distribution.

The top of my vertical was at 53 ft. and my dipole was
one of its upper guy wires at about 50 feet so the two
heights were essentially opposite yours.

No , just different..

Which brings up another question. If the top of a vertical
is at a certain height, what height of dipole would be a fair
comparison?
Dunno...But max current on the GP as at the base..


There's no "fair" comparison between two such different antennas, if
your goal is some sort of generalized conclusion about which kind of
antenna is "better". The only valid comparison would be a vertical at
whatever height you can put it at vs a dipole at whatever height you can
put it at. Then, with your particular ground conditions and azimuth and
elevation angles of interest, you can decide which is better. Any
general binary conclusion about whether a vertical or dipole is "better"
is nonsense, so there's no point in making rules for comparing them.

Roy Lewallen, W7EL

Mike Coslo January 24th 06 09:07 PM

Vertical on a tower
 
Cecil Moore wrote:
wrote:

I'm not trying to be fair.



Nuff said. I'll keep that in mind next time you
say a vertical is 24 dB better than a dipole. :-)


24 db *when* for all that matter. I would note that my vertical *is*
indeed about 2 S units noisier than my dipole. And some signals come in
stronger, and some come in weaker. My guess is that it depends on where
the signals originated from, smarter people may know the real reason.

- 73 de Mike KB3EIA -


[email protected] January 31st 06 07:39 AM

Vertical on a tower
 
Nuff said. I'll keep that in mind next time you
say a vertical is 24 dB better than a dipole. :-) ........


Well, of course, I've never said any such thing.
But...It is often a large noticable difference.

Mike sed...
My guess is that it depends on where
the signals originated from


Thats exactly it. In general, the farther away, the
better the vertical vs the low dipole.
If you don't work long haul dx, the vertical user
may never see much advantage. At night on 40m,
if the distance is less than 1000 miles, often the
dipole and vertical would be about the same.
In my case, I had to get over a 1000 miles to see
much vertical advantage. At 1500 miles, it's fairly
obvious. "appx 2 S units worth". In the long hauls
to VK, JA, etc, often 3-4 S units worth. That will
be a larger increase than your 2 s units noise increase.
Modeling won't tell the whole story in a case like
this. Just ask W8JI about his 300+ feet dipoles
on 160m. In theory , they were supposed to beat his
vertical towers. But , they usually don't on long
paths where the angle is very low.
I once yakked with this guy in Tokyo for a while.
On the dipole at 1kw, I'd be S 8-9... On the
GP with 1 kw, I'd be a solid 20 over 9. And it's
reciprical as far as xmit/rcve. So I'd always be
listening on the vertical if I wanted to see the same
increase on my end.
The only exception would be if I had something
better like a beverage, etc, but that applies more
to 80 and 160, than 40.
Thats the real point of my comments,
not which is better. To me, installing a good vertical
for dx, and then listening on a low dipole to same is
kinda silly being the benefits are reciprical.
Also...Building a good vertical, but not using it for
long hauls is kinda silly too... :/ It's the wrong tool for
working 500-800 miles away. If it's never better than the
dipole in that case, don't fret too much, as it's perfectly
normal.
MK


Cecil Moore January 31st 06 01:40 PM

Vertical on a tower
 
wrote:
Nuff said. I'll keep that in mind next time you
say a vertical is 24 dB better than a dipole. :-) ...


Well, of course, I've never said any such thing. ...


Please note the smiley face.

In the long hauls to VK, JA, etc, often 3-4 S units worth.


Well, of course, you just said it again. :-) The standardized
S-unit is 6 dB. Therefore, "4 S units" over a dipole is 24 dBd
gain for your omnidirectional vertical monopole. (That's ~17 dB
more gain than a three element Yagi has over a dipole.)
--
73, Cecil
http://www.qsl.net/w5dxp

Amos Keag January 31st 06 04:52 PM

Vertical on a tower
 
Cecil Moore wrote:

SNIPPED

Well, of course, you just said it again. :-) The standardized
S-unit is 6 dB. Therefore, "4 S units" over a dipole is 24 dBd
gain for your omnidirectional vertical monopole. (That's ~17 dB
more gain than a three element Yagi has over a dipole.)


Cecil ... you are out of context [again].

The earlier post referred to long haul DX on the lower bands where a
three element Yagi at optimum height is not easily within the realm of
possibility for us mere mortals. [ Let's see, 1/2 wavelength high on 80
meters is 135 feet, boom length for a three element Yagi at 80 meters
will approach 100 feet, You will need a football field of free space and
quite a few bucks, and the approval of several engineering firms, the
approval of you town building inspector, and the wrath of your neighbors
to compete with a simple vertical over a decent ground.] C'mon Cecil!!
Cecil ... apples and oranges ... do not enhance your reputation.

Many of us use verticals on 160, 80 and 40 meters simply because they
blow the pants off of horizontals on those frequencis for long haul DX.


Richard Harrison February 1st 06 04:28 PM

Vertical on a tower
 
Cecil, W5DXP wrote:
"I`m putting a vertical back up for transmitting and will probably
receive on my horizontal dipole."

If your grounded tower is near 1/4-wavelength on your favorite band, why
not shunt-feed the tower and use it as your radiator?

On the other hand, if you want to support another antenna and eliminate
radiation from the supporting tower, outrig a wire from the tower top,
hanging parallel to the tower, and connected to the tower top through an
L-C network tuned to make current in the outrigged wire equal ond
opposite that in the tower. The balanced currents cancel the tower`s
radiation. This may be tedious for frequency hopping, but it works.

Best regards, Richard Harrison, KB5WZI



All times are GMT +1. The time now is 02:08 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com