[Antennaware] Antennaware Digest

[Billy Cox]

Paul, lets talk about the modeling first, and then 
when the focus in more on the hardware side, that 
would be a good time to transfer the discussion to 
another forum perhaps.

Back to the modeling now ... reflect on what others
have shared with you as to their experiences ...

Here's mine ... I had a 4x 80m array around my 80'
tower with the "tie off point" for the full size
wire elements being at 70', just below my 40m yagi
which was on a TIC Ring Rotor at the time.

Rather than having the 4 vertical bases spaced out 
at about 65' for the typical 4 x setup, I ended up 
using mine at 105' ... why you ask? Good question!

When you "lean the elements tops in" using ground 
mounted or elevated feedpoints, the average spacing 
between the elements is decreased. 

So instead of having 4 elements, spaced at 0.25, we
end up with <depending on the slope> 4 elements at
a spacing of less than 0.25, and more like 0.125w,
which then causes challenges as to the proper way
to phase and match the array.

<And I believe this is why we have mixed results
reported with some of the K8UR type setups ...>

Time spent with EZNEC confirmed the need to move
the bases out ... so I offer that as a suggestion
to try there with your situation.

I would build up the 4x model, elements 100% vertical,
and the 66' x 66' spacing noting the gain/F-B/SWR/etc.

Next add in the 68' support and then tilt the verticals
toward that ... note the changes in gain/F-B/SWR/etc.

Now, moving all the bases outward by equal amounts, see
what you can do to restore the gain/F-B/SWR/etc back to
the values you noted in the typical 4x vertical setup.

That help?

73 de Billy, AA4NU

-----Original Message-----
>From: kg7hf at comcast.net
>I must be subscribed to the wrong list.   I didn't know this was only for antenna models, what a surprise, but then again, I've only been subscribed for about 2 years now, and seen maybe 10 messages go by the entire time. 
>
>If it's for modeling, why not make a model then talk about it?    
>
>How about this to get it started (and I am not so good of a model maker).   Basically, a 40m 4sq, sitting on the ground but using the ~70ft mast to hold it, they slope a littel inward.     I'm sure it could be tweaked to make it much better.   I can send the entire model if desired. 
>
>Paul, kg7hf 
>
>                 EZNEC Demo ver. 5.0 
>
>Offset Fed Yagi -Uda for QEX                 2/18/2009     12:56:36 PM 
>
>              --------------- WIRES --------------- 
>
>No.          End 1   Coord. (ft)              End 2   Coord. (ft)       Dia (in)  Segs        Insulation 
>      Conn.      X       Y       Z     Conn.      X       Y       Z                         Diel C  Thk(in) 
>1       GND        0,      0,      0                0,      0,     70       #14   1           1        0 
>2       GND       15,      0,      0              7.7,      0,     33       #14   5           1        0 
>3       GND      -15,      0,      0             -7.7,      0,     33       #14   5           1        0 
>4       GND        0,     15,      0                0,    7.7,     33       #14   5           1        0 
>5       GND        0,    -15,      0                0,   -7.7,     33       #14   4           1        0 
>
>
>
>
>Sources: 
>
>Wire #   % from E1   Phase 
>
>2                0                   0 
>
>3                0                  -90 
>
>4                0                  -90 
>
>5                0                 180