I've not had a lot of success with vertical dipoles and limited success with
1/4 verticals on 40M. However, they both have their place. I think it is
important to remember what the desired results for a particular situation. A
low dipole on 40M (say 30 to 50 feet) is an excellent high angle radiator and
is very difficult to beat fo domestic contesting and ragchewing. I have both a
quarterwave vertical (8 1/4 radials about 8 feet off the ground) and a low
dipole for 40M (as well as a high dipole) and the low dipole always wins over
the vertical for domestic stuff and is often hard to beat for DX in the same
direction. However, the vertical sometimes wins for long haul DX such as JA and
UAO.
In all cases, my high dipole at 75 feet oriented to Europe is always
significantly (6 DB or more) stronger than the vertical to Europe.
That given, I agree with Rick that if you are limited to vertical space, a 1/4
vertical with four elevated radials is a practical way to go - especially for
DX. But if you can get a dipole up to 50 feet of height, you are probably in
better shape than the vertical.
73,
Nate/N4YDU
--- On Thu, 1/6/11, Rick - NJ0IP / DJ0IP <Rick@DJ0IP.de> wrote:
From: Rick - NJ0IP / DJ0IP <Rick@DJ0IP.de>
Subject: Re: [TenTec] New and Improved Terminology (NVIS origins)
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Date: Thursday, January 6, 2011, 4:16 PM
James, that is a tough call because it is not really apples to apples.
A specific answer to your question, as compared to "my" vertical dipole,
then I must say I believe the raised quarter wave vertical with 4 elevated
radials, say about 10' off the ground will be the better antenna; but the
difference will be very little. I don't believe it would be more than 3dB,
and if anything, less difference.
If we were to take a full size vertical dipole, it would be 66' high, plus
allowing for a couple of ft. raised off the ground, you need nearly 70 ft.
This is very impractical. But then as I understand it, it would be slightly
better than the raised quarter wave with 4 elevated radials.
So my ranking:
1. Vertical dipole, full size, raised 4', total 70' height
2. Quarter wave vertical, raised 10', total 43' height
3. Vertical dipole (2x 20') raised 4' off the ground, total 44'
BUT...
#1 is expensive to implement and darn high. A 60' Spiderbeam fiberglass
pole costs $300 and would have to be extended.
#2 also needs 66' total of horizontal space (33' in 4 directions) at a
height of 10'. You will have to come up with 4 elevated tie points (trees,
house, mast, something).
#3 needs only a 40' pole (Spiderbeam: $120), plus 2x army surplus fiberglass
poles ($10) and a T-Post (fence post, $5). The mast is $135 altogether.
And the performance difference of the three, in my humble and totally
unqualified opinion, would be about like the difference between a K3, an
Orion 2, and an Eagle.
ONCE AGAIN I have to stress that I usually operated portable and options 1
and 2 would almost never have been feasible.
For my portable VD, I used the feedline as a guy wire in one direction, and
then 2x 30' pieces of thin Dacron of Kevlar rope countering it. That keeps
the antenna straight and stable (assuming a good quality heavy duty
telescoping pole, such as the Spiderbeam poles).
Bottom Line:
- For home use, I would favor option 2 (4 raised radials) if I had the
room.
- For portable use or installations with tight floor space, I would favor
option 3 (shortened VD)
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Richards
Sent: Wednesday, January 05, 2011 9:37 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] New and Improved Terminology (NVIS origins)
Do you claim your vertical dipole works better than a quarter wave with
four good, properly tuned/cut elevated radials?
Reason I ask is that my aluminum rotatable dipole project has technical
problems (The alum elements sag and dip and wave in the wind too much
-- I did not select sufficiently large diameter and stiff tubing.... but
ham radio is for experimenting, right...?) AND I was
thinking I could salvage the project by turning the floppy thing
vertical and make it a vertical dipole - OR - I might convert it into a
single tubing vertical elevated ground plane and add some wire radials.
Any traction ? (I will stick my neck out here... re: your
challenge... and expect the properly tuned elevated radials to equal the
work of the second half of the vertical dipole and say they should
perform equally well. N'est ce pas?)
================== James - K8JHR ====================
On 1/5/2011 8:42 PM, Rick - NJ0IP / DJ0IP wrote:
> I have used the vertical dipole instead of the classical vertical because
of
> my despise for radials.
> I still stand by my challenge for anyone to come up with a simple cheap
> antenna that will out-perform the simple vertical dipole.
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