Kevin:
I think vertical dipoles are wonderful. I have used them on a heavily
wooded lot with great success on both 20 and 30 meters. The higher
you can get them off the ground the better.
It is very desirable to be sure the feedline comes off reasonably
perpendicular to the antenna for a quarter wavelength or so.
Another effective trick (especially for 80 or 40) is an inverted L
fed with coax at the corner. Its almost as good as a vertical dipole.
Again, it is very desirable to be sure the feedline comes off
reasonably perpendicular to both legs of the antenna for a quarter
wavelength or so.
However, don't be too enchanted by the low angle pattern, it is also
a bit lossy. If you overlay your EZNEC vertical dipole elevation
pattern with the EZNEC broadside elevation pattern of a straight
dipole at say 5/8 wavelength elevation, you'll see that although the
vertical concentrates its energy at low angles, the actual dBi values
are not that much better than the horizontal.
W4RNL has shown that putting a very elaborate ground screen under
your vertical dipole gets you virtually no advantage. The losses are
actually from ground losses a few thousand feet from the antenna. For
that reason, if you're right on a seashore, you'll get spectacular
results in the seaward direction. (This is the Desert Island effect.)
I'm located near the coast of Maine, about 4 miles inland; the
Desert Island Effect does not help me much.
I have both a 20 m vertical dipole (center about 20 feet off the
ground) and a 20 m horizontal dipole about 45 feet up. Which one does
better depends on propagation conditions. I have worked lots of South
Pacific QRP with the vertical.
73
Steve
AA4AK
At 11:20 PM 1/11/2006, Kevin Shaw wrote:
I've been playing around with EZNEC trying to come up with a DX antenna that
will work at my QTH. The vertical dipole seems to have a fantastic pattern
for DX with low takeoff angles. I may be able to hang a vertical wire dipole
in one of my trees and have it nearly invisible. Anyone have experience with
vertical dipoles that they could share?
Thanks,
Kevin
N8IQ
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Tony Morgan
Sent: Wednesday, January 11, 2006 8:39 PM
To: Elecraft
Subject: Re: [Elecraft] QRP viability during solar cycle min?
K9QRG ON 5/12?
Just checking :>)
Tony W7GO
----- Original Message -----
From: "Larry Makoski W2LJ" <[EMAIL PROTECTED]>
To: "Darwin, Keith" <[EMAIL PROTECTED]>
Cc: <Elecraft@mailman.qth.net>
Sent: Wednesday, January 11, 2006 4:54 PM
Subject: Re: [Elecraft] QRP viability during solar cycle min?
> Darwin, Keith wrote:
>
>>K1 or K2. Hmmm, the debate continues. But wait, we're approaching a
>>sunspot min. My antennas are pretty limited. I have a 28 foot vertical
>>(fed with a tuner near the base) for 40 thru 15 and a dipole at 25 feet
>>but that is about it. No towers, no high wires, no yagis.
>>
>>How limiting will 5 or 10 watts (even with that Elecraft Mojo) be under
>>current conditions? Are we entering into conditions where QRP with
>>simple antennas will become rather frustrating? Is it K2/100 time?
>>
>>- Keith KD1E -
>>_______________________________________________
>>
>>
> Keith,
>
> Fear not fellow Elecrafter! We QRPers laugh at the sunspot minimum!
> Sunspots ...... who needs 'em?
>
> I know, actually we all do. But to be serious .... as bad as band
> conditions were in 2005, I managed to make at least one QRP CW QSO
> everyday in 2005. If you want to check out some of who I worked (and
> there was a goodly bit of DX mixed in) then please check out:
> http://www.qsl.net/w2lj/index%20page%209.html
>
> My antennas are not much more substantial (if any) than yours. I have a
> G5RV at 25 feet and a Butternut HF9V vertical which is ground mounted in
> the backyard. To me it seems that if you don't spend too much time
> concentrating on what you think are deficiencies; but go out with the
> aim to just have fun, then you will be amazed at what you can accomplish!
>
> 73 de Larry W2LJ
> K1# 1647, K2# 4090
>
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