[TowerTalk] 80 meter double extended zepp

[Chuck O'Neal]

Agreed!  I was about to make a similar comment.

It will narrow the azimuth pattern so aiming it is important
on its fundamental frequency, since its gain is nearly 3 dB
over a dipole. Also, for DX performance, on 80 M it should
be up at a reasonable height, since, like a dipole, all its
elevation gain is entirely determined by the height above
ground.  There is no reduction in elevation angle from end
fire gain as you would get from driven phased dipoles or
yagi antennas.

On the higher bands, it is a center fed longwire, resulting
in  multi-lobed pattern with gain in (very narrow azimuth)
directions that will approach, and may exceed a 3 element
yagi (particularly on 10 through 15M)!   Modeling is a very
good idea to see what you will actually get.  Unfortunately,
this antenna, like all long wires, will produce a null
broadside to it at the higher frequencies where it much
longer than a wavelength long, so that if you aim it at
Europe at its fundamental frequency, it will have a null in
that direction on many of the higher frequencies .

73,
Chuck...K1KW

----- Original Message ----- 
From: "Tim Duffy K3LR" <k3lr at k3lr.com>
To: "Thomas Rieff" <kc0pyk at yahoo.com>; "Towertalk"
<towertalk at contesting.com>
Sent: Thursday, June 03, 2004 7:05 PM
Subject: Re: [TowerTalk] 80 meter double extended zepp


> The double extended (two 5/8 wave elements) zepp is one of
my all time favorite wire multi band antennas. I just picked
up two of this exact antenna from open wire guru, W7FG,
earlier this week This antenna has gain over a standard 1/2
wave dipole (almost 1.8 dB on 80 and more on the higher
bands).  It should be fed with open wire the whole way (no
coax, no baluns, no magic boxes) to a high performance
antenna tuner that is balanced line capable. In my
> opinion the best tuner for this application is the Johnson
Matchbox. I have also had good success with the Heath 2060
and 2060A. Sure you have to adjust the tuner when you QSY,
but the performance of the antenna is super! There is no
free lunch!
>
> 73!
> Tim K3LR
>
> http://www.k3lr.com
>
> Thomas Rieff wrote:
>
> > I recently built a 80 double extended zepp using the
HamCalc configuration.I cut the lengths for 3.555 MHz.
Hoping for a broader multiband performance with a tuner. The
lengths are as follows...168.4 ft for each top leg and 38 ft
of 450 ohm ladder line for the matching section and then
into a 1:1 current balun.
> > My question is should the swr be 1:1 for the design
frequency, is it attainable, or are double extended zepps
inherently a high swr antenna. It currently runs about 5:1
without the tuner and goes higher on the other bands.I have
not done any trimming or adding to the antenna lenghs. The
information says to trim the ladder line matching section
for lowering the swr. Another source I found said that the
ladder line matching section should be cut at 30 ft.
> > I see a couple of options; scrap the balun and coax and
run ladder line directly to the tuner, start trimming the
ladder line (what is a reasonable amount per test?), scrap
the antenna entirely and put up something else. I recently
built a 40 meter loop with 72 ohm matching section and it
worked perfectly 1:1, at its design frequency. I have a fair
amount of room to put up wire.
> > Your thoughts are appreciated.
> > Tom KC0PYK
> >
> >
> > KC0PYK
> > Thomas Rieff
> > 2059 Sundance Lane
> > North Mankato, MN 56003
> >
> >
> > ---------------------------------
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> >
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>
> See: http://www.mscomputer.com  for "Self Supporting
Towers", "Wireless Weather Stations", and lot's more.  Call
Toll Free, 1-800-333-9041 with any questions and ask for
Sherman, W2FLA.
>
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