Tom,
One further comment...
Greg, W8WWV has recently modeled the 160 meter parasitic array that I use
with EZNEC. The real world F/B was exactly where Greg said it would be.
This gives good confidence of predicting performance when analyzing this
type of antenna through computer modeling.
73!
Tim K3LR
-----Original Message-----
From: Tim Duffy K3LR [mailto:k3lr@k3lr.com]
Sent: Monday, January 07, 2008 5:07 PM
To: 'Tom Osborne'; 'Towertalk'
Subject: RE: [TowerTalk] Phasing Question
Hello Tom!
I have been using a parasitic array on 160 meters for years with great
success. My parasitic elements (4 of them) are all cut as directors. There
are 3 modes to the end of these elements. I am using an extensive ground
system under each element as well. The elements are spaced 1/8 wavelength
from the tower.
The 3 modes are:
Ground (Director)
In series with a coil (Reflector)
Float (not used)
The array is described in the 3rd and 4th edition of the ON4UN low band
DXing book. VE3EJ, AA1K and others have also built this parasitic vertical
Yagi. I know N6TR is experimenting with parasitic elements as well.
73 and Happy New Year!
Tim K3LR
http://www.k3lr.com
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Osborne
Sent: Sunday, January 06, 2008 11:34 PM
To: Towertalk
Subject: Re: [TowerTalk] Phasing Question
Jim Wrote:
>
>
>
> But.. in a multi element array, there's more to it than just the length of
> the coax.. the elements interact with each other (mutual impedance), so
> the feed point impedance of element 1 varies depending on what you're
> feeding elements 2,3,4, etc. with.
I asked this same question here a couple of months ago, and from what I
received in answer, I assume unless you have a meter to detrmine inpedance,
reactance, phase angles, vectors, etc, it is not worth doing to do it right.
So, there is another question I have. If you just put up 1 vertical and put
up another one 1/4 wave away, can you use this as a director or reflector by
switching a coil in and out?
This seems like it would be a lot easier to do. Thanks and 73
Tom W7WHY
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