[TowerTalk] HF-VHF-VHF Stacked Yagi's on Single Mast

[N6FD]

I have used the 4nec2 program with good results modeling my VHF stack.  
Its interface is quite good and the price is free.

Its also pretty good for modeling HF antennas although you may have to 
play with the ground impedance parameters for your location.

73 Erich
N6FD DM15dp

On 12/29/2013 11:06 AM, john at kk9a.com wrote:
> I have YO, AO and EZNEC+.  I would recommend purchasing
> http://www.eznec.com/ .  The 2m and 6m beams should be pretty easy to model,
> the X7 is not.  I suspect that your system will work fine as proposed but it
> is still nice to model and see what is happening.   I modeled every antenna
> on my tower  trying to minimize interaction however there are always
> compromises.
>
> John KK9A
>
>
> To:<TowerTalk at contesting.com>
> Subject:Re: [TowerTalk] HF-VHF-VHF Stacked Yagi's on Single Mast
> From:"N8GLS" <n8gls at arrl.net>
> Reply-to:n8gls at arrl.net
> Date:Sat, 28 Dec 2013 20:46:52 -0500
>
> Thanks All for the comments.
>
> K5GO (Stan), Oops, yes, the longest element on the 6m beam is 10 Ft, not 5
> Ft.  Yes, I am aware of the differences of stacking same band antennas
> versus just stacking different band antennas on a single mast.  Please see
> my general comments below.
>
> KK9A (John), Yes, I would like more mast nested inside the tower as well.
> When I got the 1026 DOM mast I said to myself, &*%$#, that?s heavy, and
> LONG.  That?s why I keep putting the 6m beam at the top, with its paltry 2.2
> Sq Ft of wind area, albeit at 12 Ft atop the mast.
>
> W1DYJ (Larry), thanks for re-directing me back to that very good article.  I
> did read it some time ago along with several others and many many comments
> on various other formulas and/or rules of thumb, most of which aren?t much
> better than a guess....which is why I come to the pool of experts here !!
>
>
> All aside, it seemed to me that if I centered everything around the highest
> frequency band (2M in this case) and try to keep everything out of its
> aperture then all should be good with the world.  With the 6m beam at approx
> 5 Ft above and the HF tribander at 5 Ft below, both are just inches inside
> the aperture of the 2M beam, but it isn?t seeing much of that metal as there
> are few elements and they are very wide spaced.  The HF tribander is
> completely outside the aperture of the 6m beam, yes the 2m beam is way
> inside the aperture of the 6m beam but with its large aperture coupled with
> the "small" elements of the 2m beam I didn?t think that it would result in
> any major loss in gain.  I can't guess on the effects it may have on SWR.
> Several of you mentioned modeling the stack to get a better idea, what
> software are you all using??
>
> Brad, N8GLS
>
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