Hello Wayne.
31 Mar 97 21:42, Wayne Sarosi wrote about VHF/UHF-4:
I've built them like this for Cox Cable Communications here in San Diego.
There's no problem with the mast interferring with the radiation pattern.
       || <- tower leg
       ||
       ||
       ||      |    |    |    |    |   |
     [.||.]    |    |    |    |    |   |
()---| [] |----|----|----|----|----|---|- <-- VHF/UHF Yagi
CB   [ù||ù]    |    |    |    |    |   |
       ||      |    |    |    |    |   |
       ||      R    DE   D1   D2   D3  D4
       ||
       ||
       ||   CB = counter balance, if required.
   Try Testing a Yagi antenna for pattern and gain with the antenna mounted 
like the above.  Most, but not all, commercial antennas I've seen are built 
with the mounting bracket on the rear of the boom.
I've built a stacked pair of UHF Yagi's, modeled by Yagi Optimizer.  The 
spacing that YO modeled was unusual, in that the directors were spaced 
differently than most yagis.  Not a problem, as it works great.  I've already 
worked stations simplex in LA with a 5 element yagi (also modeled by YO) with 
a 10 watt radio.  Yagi mounted on a 15-16 foot mast (roof line), since I live 
in a antenna restricted community.  Below is the method of mounting I 
incorporated with the 5 element and now the stacked 6's.
               |    |    |       |       |       |
       ||      |    |    |       |       |       |
     --[]------|----|----|-------|-------|-------|-
       ||      |    |    |       |       |       |
       ||      |    |    |       |       |       |
       ||      R    DE   D1      D2      D3      D4
       ||
       ||
According to YO, the stacked array has 13.6dbd gain with a 25db F/B ratio.
Since the yagis shouldn't be affected by the stacking kit or the mounting 
mast, the pattern should be normal.  I say, that if the yagi's are matched 
with a gamma on the outside of the stacked array, the pattern will be normal. 
 YO won't model it with the gamma in place, just tells me it'll work and 
shows a pattern of the antenna.  I've been  told that if the yagis are 
matched with a gamma and each gamma is mounted on the right or left of the 
yagi, it will affect the pattern by skewing it right or left, ie; gamma 
mounted right, pattern skewed right and vicea versa. What's your opinion?
Here's a top view illustration of what I'm talking about.
               |                                    |
               o D4                                 o
               |                                    |
               |                                    |
               o D3                                 o
               |                                    |
               |                                    |
               o D2                                 o
               |                                    |
               |                                    |
               o D1                                 o
               |                                    |
gamma match-> o0 DE                                 0o <- gamma match
               |              top view              |
               o R          gammas mounted          o
               |            outside stack           |
               |                                    |
              ===================()===================
               |           stacking boom            |
               |                                    |
If I moved the left gamma inboard, would the pattern be skewed right?  If I 
moved both gammas inboard, would the pattern be narrowed?
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