I'll just add to the discussion that there's a HUGE effect of terrain at
Ranko's station, having visited there in 2016 (before the fire). The shot
to the US is off the side of a big dropoff (560m elevation) that drops
non-stop to sea level to the Bay of Kotor and then eventually comes back up
some number of kilometers away across the bay. The closest topography that
I can think of, Ranko, would be Bill KH7XS's on the Big Island, except it is
open water to the horizon in his case. So it's difficult to intuitively
predict what the impact of vertical stacking is. We talked about that at
your station, there was concern by you that HFTA modeling may not give
accurate results when you're skirting a hill instead of directly down a hill
(i.e. following the gradient), which I agree. However, I would still do
the modeling and see what you get. You may be surprised that lower
antennas will outperform high stacks. I'm sure Bill KH7XS could comment
about that, keeping in mind arrival angles from the US at KH7XS are much
lower than they than they are in 4O.
I've heard you many times in contests, Ranko, when you were one of very few
stations coming in from Europe with a very strong signal. But I've also
heard you surprisingly weak when others in Europe were very strong.
I assume the objective of your antennas is to maximize gain vs. F/B (there's
not much to the back of you when you're working the USA). In your
situation with that topography, perhaps horizontal stacking of high-gain
long boom antennas is the way to get gain (vs. vertical stacking), keeping
in mind that you will lose azimuthal beamwidth.
I would try to do some HFTA modeling to at least get a feel for the effect
of antenna height in your very unusual topography and then go from there.
I have a suspicion that you may not need as much tower height as one might
think.
--- Rich K1CC
> When making something big, such as a life time contest project, it is
> better to share and listen for advice. Here we have an experienced group
of
> contesters and maybe someone has something to say that I am not
considering
> at the moment?
>
> I am intending to rebuild the 4O3A station. One of the tasks is to put two
> towers in stack toward USA.
> On each tower I will have a stack of 2L40, together with a tribander
stack.
> The idea is to optimize horizontal distance of towers on 40M and 20M.
Other
> bands can't be optimized, and are not that important.
>
> I am still looking for tribanders designs, either to buy them or to build
> them.
>
> Any advice is welcome.
>
> 73
> Ranko
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