[Elecraft] non-Wire antennas

Tue Feb 19 21:17:06 2002

I have an idea or two. It's working, don't mess with it. What's wrong =
with 1.7:1 anyway on one band of a 9 band, ladder fed doublet? There's 2 =
1.5:1's and a bunch lower still.

Dan / WG4S / K2 #2456

-----Original Message-----
From: Bob Tellefsen [mailto:[email protected]]
Sent: Tuesday, February 19, 2002 7:53 PM
To: Dan Barker
Subject: RE: [Elecraft] non-Wire antennas

Hi Dan
Think of "a little" as being frequency sensitive, like about 1/16th
wavelength.
On 10m that would be about 2 ft, while on 80m it would be more like 33 =
ft.
The main idea is to move the transmitter feedpoint away from a very high
impedance
point on the feed line.

As an example, consider a 40m halfwave dipole fed with 450-ohm line.  If =
the
antenna is pretty close to resonant, and the feedline length is adjusted =
for
a current maximum (lowest impedance) at the shack end, it will be very =
easy
to match and load.  The feedline will be a halfwave long under these
conditions, repeating at the shack what it sees at the antenna.  Now =
shift
to 20m.

The 40m halfwave dipole is now two halfwave dipoles on 20m, center fed =
at a
high Z point.  The feedline is now 2 halfwaves long, and that high =
impedance
is repeated at the shack end.  If you add about 1/16th wavelength of =
line,
it will lower the impedance enough for fairly easy matching.

I use 450-ohm line as my feeder on my multiband dipole.  To change =
bands, I
plug in an extension section of line to bring the low Z feedpoint back =
to
the end of the line.  I Use banana plugs and jacks to make the line =
addition
quick and easy.

Hope this gives you an idea or two.
73, Bob N6WG
Newark, CA
on SF Bay
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Dan Barker
Sent: Tuesday, February 19, 2002 12:42 PM
To: Elecraft
Subject: FW: [Elecraft] non-Wire antennas

Stuart: I'm wondering at the meaning of the technical term "a little". =
Is it
most like a centimeter, an inch, a foot, a cubit, a meter, a fathom or a
furlong?

Dan / WG4S / K2 #2456

-----Original Message-----
From: Stuart Rohre [mailto:[email protected]]
Sent: Monday, February 11, 2002 1:37 PM
To: Dan Barker; Elecraft
Subject: Re: [Elecraft] non-Wire antennas

Dan,
Add a little ladder line, and it will load on the other band.
73,
Stuart k5KVH

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