Brad,
It was relatively easy to model a fairly large 2m antenna design I had with a
small 5 element 6m antenna above it by 5 feet. In the case of the two antennas
I used in free space the degradation in gain was only .4 dB. The SWR was
nearly identical and the front to back was actually about 4 dB better.
73...Stan, K5GO
Sent from my iPad
On Dec 28, 2013, at 4:54 AM, Stan Stockton <wa5rtg@gmail.com> wrote:
> Brad,
>
> There may be a misunderstanding. You are talking about installing a few
> antennas on a mast.
> When you refer to capture area(s) and recommended stacking distances it
> sounds like you are looking at some information by some manufacturer on what
> they recommend for stacking two or more identical antennas to be fed in
> phase. Of course those are entirely different things.
>
> What you won't find from many manufacturers is how a particular antenna is
> affected by another particular antenna placed a certain distance apart.
> There are too many combinations and variables. I can tell you is that it is
> sometimes a real eye opener to see the resulting interaction and degradation
> of performance, after taking the time to properly model antennas in proximity
> to each other.
>
> It looks like 2m is important to you since that is by far the longest boom
> you have. The question is whether the 6m antenna will dramatically affect
> the 2m antenna performance. You mentioned the longest element on the 6m
> antenna being 5 feet. That sounds like a quarter wave on 6m. Surely it is
> about 9-10 feet instead?
>
> 73...Stan, K5GO
>
> Cycle 24 Antenna Products LLC
>
>
> On Dec 27, 2013, at 11:32 PM, "N8GLS" <n8gls@arrl.net> wrote:
>
>> Group,
>>
>> I have a Hygain HG-54HD Crank-Up Tower which had a Hygain TH5MK2 HF tri-band
>> Beam and a Cushcraft 17B2 2m Boomer all on 8 Ft of mast (10 Ft total with 2
>> Ft inside the tower). I’m adding an M² 6m Yagi, changing the TH5MK2 beam for
>> a Cushcraft X7 (w/40m add-on kit) and keeping the Cushcraft 17B2 2m Boomer.
>> All to be on 12 Ft of new 1026 DOM Mast (14 Ft total with 2Ft inside the
>> tower). The stack will be as follows, from bottom to top;
>>
>> At 2 Ft from top of tower---Cushcraft X7 (HF 40m-20m-15m-10m), 18 Ft boom, 6
>> elements, longest element 40 Ft, 9.9 Sq Ft wind area.
>> At 5 Ft above the X7---Cushcraft 17B2 (2m) Boomer, 31 Ft boom, 17 elements,
>> longest element 3.5 Ft, 3.9 Sq Ft wind area.
>> At 5 Ft above the 17B2---M² 6M5X (6m), 18 Ft boom, 5 elements, longest
>> element 5 Ft, 2.2 Sq Ft wind area.
>>
>> At the end of the day, I have 12 Ft of mast to stack the above mix of beams.
>> The spacing above is in order of wind surface area, which is my main
>> concern. I have looked at capture area(s), recommended stacking distances,
>> and I end up needing a mast length that is not feasible for the tower. So,
>> does anyone have a better stacking arrangement than the above ???
>>
>> This project started out as just taking down the old tower and painting
>> it…..then after seeing it’s not going to be easy to drop that thing without
>> some kind of raising fixture I bought a new US Tower raising fixture and
>> re-vamped it to fit the HyGain base, bought the new 6m yagi, then the
>> Cushcraft X7, all new coax and rotor cable, new mast, and now I decided to
>> have the tower re-hot dip galvanized instead of painting it (cant paint in
>> winter)……..and of course it’s December, the end of December actually, in
>> northeast Ohio, need I say more ?? Oh ya, and I’d like to get this done
>> before the VHF contest in a few weeks….Ha….
>>
>> Thanks for any comments on the stacking…..my XYL is already giving plenty of
>> commentary on all the other….
>>
>> 73 de Brad, N8GLS
>>
>>
>> _______________________________________________
>>
>>
>>
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