> You are asking very good questions that I think have pretty simple
> answers but are easy to confuse. Since it's all a compromise with
> these antennas pick the most important parts for you and try to
> optimize them. Gain is going to be similar since it's mostly related
> to boom length, but bandwidth, pattern and coverage of WARC
> bands could be deciding factors for your purpose(s).
Yes. WARC coverage is nice, though I've not accessed the WARC
bands much yet. My application is mostly emergency and missionary
traffic, kinda opposite since the first is largely local and the other DX
with weak signals under often poor conditions. I probably should
have something at 45 and something at 70 feet.
> It won't be fair to compare the T10 to a C3 or the C3s as the T10
> has a much longer boom and gain is driven by boomlength, not
> number of elements. Models and real world measurements will
> show that for well designed antennas of similiar boom lenght the
> gain will be similar. Pattern (F/B, F/R, F/S) could well be better
> with the Log than the C3 which is two elements on 20 and 15 and
> has a minimal cardiod type pattern. Of course it depends what you
> want to work, where you want the nulls and what height the
> antenna is mounted at (very important). In any case, your antenna
> selection and installation parameters should fit your needs, not
> simply have the best "specs" on paper.
Ayuh. But doesn't the Force 12 design get some "help" from some
of the other elements, sorta like the LPDA concept?
> The Log may also have better bandwidth, although I've never seen
> this be an issue in real life with the antenas we are talking about.
> Trade off for the Log is more windload (generally) than a similar
> tribander and a more complicated feed system.
The Tennadynes seems to have a pretty sound system, or so several
users have said. Wonder why KMA and SOMMER LPDA folks have
been so silent?
> FWIW, I've used a good log at W6EEN for the last few contest
> seasons. On 20M Don has "only" a 6L at 105 feet which is not
> great for close in stuff, but killer on DX. The Log is a 60 feet and
> has an ~30 foot boom. It is a very fine antenna and compares well
> to any tribander or 3L beam that I've used at a similar height.
> That's anecdotal of course, but in a world of compromises, the Log
> does fine. It is not a long boom yagi and it is not going to be 4S
> units better than a similar size tribander (at the same height), but it
> will perform in similar fashion.
Log proponents seem to be fond of comparisons to trapped tri-banders
but have so far avoided comparisons to the Force 12 trapless designs.
On the other hand yagi proponents seem fond of comparisons to
monoband designs, also unfair.
> My $0.02 on this is if you want WARC or perhaps general coverage
> receive, then consider a Log. If you just want 10/15/20 meters put
> up the longest boom tribander you can. If you can move up from
> the C3 to a C19 or Bencher Skyhawk it should be worth the effort.
Part of my consideration is size, part is cost ... more is cost. Plus I
want something that can take the abuse of the frequent high winds
and the constant humidity here.
> Remember, all the manufacturers bend the truth when talking about
> gain and F/B because they take the optimal point in each band to
> report the numbers. At least Tom states the height that they
> modelled at for their gain figures. Of course it's ~1 wave at 20M
> and almost ~1.5 for 15M and ~2 wave at 10M which makes 75 feet
> a very nice height to model at to get good looking numbers. But
> Tom's a smart guy.
Well, 75 feet is a good height to get over trees and all as well. I'm sure
their marketing folks looked closely at the numbers when they picked
that height. I can get to 70 feet with a longer mast, and the soil here is
very sandy (though there are lots of small trees below) so I am guessing
the numbers won't vary too much from 75 to 70 feet here.
> Many of the new trapless tribanders are overlayed 3 and 4 element
> monobanders with some coupling to the extra elements.
> Performance of 2 and 3L yagis is well established so you can
> make your own good call about how things should perform for you.
> To my knowledge, nobody has gotten any magic over anyone else
> and in the end it's more fun to get on and make contacts than to
> sweat 0.25 db on a gain figure or 3 db on F/B.
> Mark
> KI7WX
Ayuh. Solid construction, predictable performance across weather and
within bandwidth are both key factors ... affordability is too! ;-)
Thanks for your helpful comments!
73, DavidC K1YP
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