A vertical dipole with the feedline coming straight off of the side for at
least 1/4 wavelength should have a near prefect circle/round pattern. This
of course can be impacted by variations in ground resistance in the near
field. Should the feedline not exit for 1/4 wave there will be some
interaction with the radiation patter.
Another antenna configuration, vertical polarization, is the coaxial
radiator. It is center fed with coax, reasonably easy to construct for
frequencies higher than 14 MHz and exhibits a near perfect round pattern.
However, it typically lends its operation to a single band.
Here's some examples.
http://www.hamuniverse.com/17mcoaxmox.html
http://www.tpn7055.ca/40coax.html
http://www.alpharubicon.com/elect/alphabazookaKatunk.htm
73
Bob, K4TAX
----- Original Message -----
From: <ve1bn@ns.sympatico.ca>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Thursday, July 14, 2005 8:07 AM
Subject: Re: [TenTec] Vertical Dipole "Fringe Benefits"
> Gary -
>
> At least you don't need a rotator.
>
>
> ----- Original Message -----
> From: "Gary Hoffman" <ghoffman@spacetech.com>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Wednesday, July 13, 2005 9:56 PM
> Subject: Re: [TenTec] Vertical Dipole "Fringe Benefits"
>
>
>> Me too. I still have a multi-band vertical up, but of course its not a
>> half
>> wave dipole. Even so, it compares reasonably well with my beam. (That
>> is,
>> the beam is better, but not by an overwhelming margin). So, going to a
>> half
>> wave vertical dipole might be quite effective, as well as fun. Of
>> course,
>> the front to back would be terrible by comparison.
>>
>>
>> ----- Original Message -----
>> From: "Robert & Linda McGraw K4TAX" <RMcGraw@Blomand.Net>
>> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
>> Sent: Wednesday, July 13, 2005 9:08 AM
>> Subject: Re: [TenTec] Vertical Dipole "Fringe Benefits"
>>
>>
>>> I agree. All this discussion, while not directly Tentec related, has
>>> got
>> me
>>> to thinking about putting up a vertical dipole.
>>>
>>> 73
>>> Bob, K4TAX
>>>
>>> ----- Original Message -----
>>> From: "NJ0IP" <Rick@DJ0IP.de>
>>> To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
>>> Sent: Wednesday, July 13, 2005 4:59 AM
>>> Subject: [TenTec] Vertical Dipole "Fringe Benefits"
>>>
>>>
>>> > Ten-Tec is my first love in radio equipment, that's why I'm on this
>>> > reflector.
>>> >
>>> >
>>> >
>>> > I guess it's time for Ten-Tec to release a new product because we
>> haven't
>>> > seen much complaining here for quite some time now (hi).
>>> >
>>> >
>>> >
>>> > Until then, I am enjoying these antenna discussions.
>>> >
>>> >
>>> >
>>> > THE VERTICAL DIPOLE AND 80m SURPRISE: DX better than on the full size
>>> > dipole.(often)
>>> >
>>> >
>>> >
>>> > I put up the vertical dipole for the first time ever in 1993 when I
>> moved
>>> > into my previous QTH, which didn't have much ground space.
>>> >
>>> > I took it down once I got the beam and openwire fed horizontal dipole
>> up.
>>> >
>>> >
>>> >
>>> > Here at the new QTH I use the vertical dipole everyday, though each
>>> > side
>>> > is
>>> > now 1m longer than it was at the previous QTH.
>>> >
>>> >
>>> >
>>> > I have had horizontal dipoles (dublets) fed with openwire at my last 3
>>> > locations.
>>> >
>>> > Each was a different size, based on the space I had available.
>>> >
>>> > All were about the same height: 13m (40 ft.).
>>> >
>>> > They were: 2x 20m (now, used 6 years), 2x 10m previously (used 7
>>> > years),
>>> > and
>>> > 2x 13m (used 5 years)
>>> >
>>> >
>>> >
>>> > The first interesting question might be, how did these 3 compare?
>>> >
>>> > Hey, this is about as subjective as it gets, because they were used
>> during
>>> > different times, different sunspot cycles and at different locations.
>>> >
>>> >
>>> >
>>> > My highly subjective gut feeling, for 40m and above, all performed
>>> > about
>>> > equally well.
>>> >
>>> > For 80m, the 2x13m performed about the same as the 2x20m and the 2x10m
>> was
>>> > noticeably weaker. This is based on my ability to work multis in
>> contests
>>> > with the first or second call, as well as the day to day reports I got
>> in
>>> > my
>>> > 80m skeds.
>>> >
>>> >
>>> >
>>> > Now the surprise. I have always tried to orient these horizontal
>> antennas
>>> > such that I could have the major lobe facing stateside, and as a
>>> > result,
>>> > working Asiatic Russia has always been a real challenge. In contests,
>>> > I
>>> > could hear those guys 599 for hours but simply couldn't work them.
>>> > Eventually I would snag one but the time wasted wasn't helping my
>> contest
>>> > score.
>>> >
>>> >
>>> >
>>> > At the last QTH, 2x10m, I pulled the openwire feedline out of the
>> Annecke
>>> > and stuck just one side of it into an MFJ Differential-T. My only
>> ground
>>> > was the cold water pipe. I had no radials or counterpoise. This was a
>>> > panic
>>> > effort in the middle of a CQWW to try and work UK9/0. Hey, I worked
>>> > it
>> in
>>> > a
>>> > relatively short time. This tells me the radiation pattern of the
>>> > "Inverted-L" which I had converted my horizontal dipole into was more
>>> > favorable for the east in that configuration than in the classical
>> dipole
>>> > configuration. Remember, I had already taken down my vertical dipole
>> and
>>> > didn't have it.
>>> >
>>> >
>>> >
>>> > Here at the new QTH, I have the vertical dipole. I found I can call
>>> > for
>>> > hours using the horizontal dipole and still don't manage to work
>>> > UK9/0 -
>>> > even with maximum legal power. However, switching to the vertical
>> dipole,
>>> > I
>>> > can work them even with 100w with just a few calls.
>>> >
>>> >
>>> >
>>> > So two years ago, I worked a CQWW single band 80m from home and spent
>> most
>>> > of the time just switching between antennas. For transatlantic work
>>> > it
>>> > was
>>> > a wash. One time the signal was louder on the horizontal (full size
>>> > up
>>> > 13m), the next time it was louder on the vertical. For working the
>>> > European
>>> > multipliers, the horizontal was almost always a couple of S-units
>> louder.
>>> > Asiatic Russia only worked on the Vertical Dipole.
>>> >
>>> >
>>> >
>>> > The following year (last year) I stayed home again for CQWW but didn't
>> put
>>> > in a serious effort. Still, I made another valuable experience. On
>> 40m,
>>> > the vertical dipole was almost always 1 S-Unit better than the 2x20m
>>> > horizontal on long-haul, but the big surprise was that for EU
>> multipliers,
>>> > the vertical dipole was also stronger - almost always, except for the
>>> > countries which are very close to Bavaria.
>>> >
>>> >
>>> >
>>> > The Bottom Line: It's sure nice to have two antennas instead of just
>> one.
>>> > The vertical dipole is a significant enhancement to my station even on
>> the
>>> > low bands, where I, for many years, only had a horizontal dipole.
>>> > This
>>> > was
>>> > a pleasant surprise because I had initially put the vertical up for
>>> > the
>>> > high
>>> > bands.
>>> >
>>> >
>>> >
>>> > 73
>>> >
>>> > Rick
>>> >
>>> >
>>> >
>>> >
>>> >
>>> > _______________________________________________
>>> > TenTec mailing list
>>> > TenTec@contesting.com
>>> > http://lists.contesting.com/mailman/listinfo/tentec
>>>
>>>
>>> _______________________________________________
>>> TenTec mailing list
>>> TenTec@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>>>
>>>
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|