[TowerTalk] Full wave loop on 80m : Impedance 50 or 75 Ohms??

[Lee Noonan]

Thanks Bob
Lee VK2LEE


----- Original Message -----
From: "realex" <realex at flash.net>
To: "Lee Noonan" <vk2lee at maxnet.net.au>; "Towertalk"
<Towertalk at contesting.com>
Sent: Wednesday, January 29, 2003 12:16 PM
Subject: RE: [TowerTalk] Full wave loop on 80m : Impedance 50 or 75 Ohms??


> A vertically mounted full wave loop that is rectangular ( twice as high as
> it is wide) will have a feedpoint
> Z of around 40 ohms when fed in the center of the short side nearest the
> ground.  Since you state your loop is
>  horizontal and 1/8 wavelength high, I would think the feedpoint Z is less
> than 40 ohms.  If that is the case,
> the 50 ohm line is the better choice.
> 73, Bob, W5AH
>
>
>
> -----Original Message-----
>
> 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...
> 73
> Lee Noonan  VK2LEE
>