I feed mine with 450 ladder line and a 1:1 choke balun
in the shack just before my tuner (kat2). I can work
all bands with this config and it really gets out,
much better than the could burner reputation would
suggest. I have measure the impedance at around 90 on
80 and from 36 to 600 on other bands. The tuner
cleans it up and it really sings for me.
btw: I feed it with coax for the first 2 years and
what I found was the losses in the coax made it look
like it was a good match on other bands but it really
wasn't. I got a real big improvement just by going to
ladder line, nothing else was changed.
--- Jon Ogden <firstname.lastname@example.org> wrote:
> Dug out an old textbook from my antenna class in
> college (Antenna Theory and
> Design by Stutzman and Thiele). On page 250 of the
> book they are discussing
> full wave loop antennas.
> "The square loop antenna is most useful in practice
> for a one-wavelength
> perimeter becuase of the desirable input impedance
> input resistance for a one wavelength perimeter is
> about 100 Ohms."
> Unless I am reading something wrong, it appears that
> 100 Ohms is your
> The antenna with the impedance range between 50 and
> 75 is the dipole. A
> resonant half wave is about 70 Ohms.
> Now, I forget what happens to the impedance when
> parasitic elements are
> added as in a Quad.
> If I am incorrect, I am more than willing to be
> on 1/27/03 9:15 PM, Lee Noonan at
> email@example.com wrote:
> > I have been using Full wave loops on 80m since
> 1987 and have always used 75
> > Ohm coaxial cable as feedline without a Balun. I
> know of other hams that use
> > a Balun on a full wave loop. My Loop is
> Rectangular in Shape and fed in the
> > center of one of the shorter sides. The Antenna is
> terminated with a gap of
> > around 3 inches between the ends.
> > This was how it was described , for a German Quad
> antenna which is a Full wave
> > loop in a Diamond shape terminated at one of the
> sharp pointed ends..The
> > German Quad was Quoted with an Impedance of
> roughly halfway between 50 & 70
> > Ohms Impedance.. My Quad antenna is 33 feet high
> at all 4 points. Any
> > Comments on what impedance this Antenna May be at
> the feed point and how to
> > feed it with Coaxial cable... I am about to run
> ALL new cables thru the roof
> > of My House and I'm wondering whether to use 50 or
> 75 Ohm Cable...
> Jon Ogden
> NA9D (ex: KE9NA)
> Citizen of the People's Democratic Republik of
> Life Member: ARRL, NRA
> Member: AMSAT, DXCC
> http://www.qsl.net/na9d <- Updated on 1/22/03!!!
> "A life lived in fear is a life half lived."
> TowerTalk mailing list
- Jim Apple (WB1DOG)
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