Given the short distance between top and bottom antennas, is there a
benefit to this kind of array vs. interlaced monobanders on a common
boom?
That's exactly the reason I asked if the monobanders had been optimized
for stack use. Study after study shows the 15 meter antenna is badly
impacted in these "close" stacks - even if the SWR stays fairly close
to nominal. The 15 will affect the 10 but not as badly as the 20
affects the 15.
Years ago I had a 204/155/105 stack put up with Hy-Gain's recommended
spacing (I think it was 7' from 20 to 15, 5' from 15 to 10) and the
15 never really worked as well as it should have. I moved the 204 to
another tower (stacked it with a second 204) and brought the 15 down
so there was a full 12' between 155/105 and both antennas performed
a lot better. Knowing what I do now, I should have found a way to get
the 105 a full 16' above the 155 ... or optimize the 105 for the
presence of the 155.
73,
... Joe, W4TV
On 2014-12-11 2:49 PM, Kelly Taylor wrote:
Can I step back and ask a bigger-picture question?
Given the short distance between top and bottom antennas, is there a benefit
to this kind of array vs. interlaced monobanders on a common boom?
In Fudo's case, perhaps he is using existing antennas and isn't in a
position to replace them with something such as a long-boom F12 antenna, but
in a from-scratch installation, is there any reason to move to the
mechanical challenges of stacking antennas like this so close together vs.
using just one antenna?
73, kelly
ve4xt
On 12/11/14 1:35 PM, "n8de@thepoint.net" <n8de@thepoint.net> wrote:
I agree with Joe, W4TV, but, would add the comment:
PUT THE 20M monobander on TOP of the stack .. that is .. invert it,
with the 10m on the BOTTOM.
73
Don
N8DE
Quoting "Joe Subich, W4TV" <lists@subich.com>:
Unless the monobanders have been designed to operate in a stack
("Christmas tree"), stacking them as closely as will be needed to
stay within your 5m mast will certainly reduce their performance.
If the monobanders have been optimized to work in a stack, use the
spacing for which they were designed.
73,
... Joe, W4TV
On 2014-12-11 9:16 AM, Fuad Arnautovic wrote:
Hi all
I need advice from some more experienced with stacking about possible setup.
Have self-standing tower abt 18 mtr, mast 50 mm (2") 5-6 metres long
Antennas are three monoband yagis as follows
20m 4el 9,5m boom
15m 5el 9,6m boom
10m 5el 7,6m boom
Does it "Christmas tree" setup working well with this monobanders?
What is your recommendation for vertical spacing between? Does 2"
mast is strong enough to support all them.
I would install lowest antenna for 20m then 15m and on the top 10m
I know that is compromise against performance and radiation
pattern, but actually cannot install another tower
Please help
Thanks in advance
Fudo, E73CQ
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