In the flurry of posts I've made to this reflector in the past several
weeks concerning big tribanders and 4-square arrays, the issue of F/B ratio
came up time and time again. For the tribanders, the issue was that the
TH7DX appears to have much better F/B than the KT-34XA. For the 4-square,
the issue was how operating away from resonance or construction assymetry
significantly affects F/B.
However, a couple of replies I got brought to the fore a question I've been
kicking around in my head for a long time: Just how important is F/B,
anyway?
Now, remember, this question comes from someone who has only had one measly
roof-mounted TA-33M for about two out of his 15 years as a ham -- and has
operated with verticals and dipoles for the rest of that time. Thus, as an
operator of mostly omnidirectional antennas, I haven't had the pleasure of
coping with the pluses and minuses of a big F/B ratio.
The replies basically pointed out that the big F/B ratio on the TH7DX is
actually something of a pain -- there are many situations where you have to
turn the beam clear around to talk to someone off the back. I assume that
this mostly applies to nets.
It seems to me that in many contests, a big F/B can be a real liability (as
some pointed out to me.) While you want to point the antenna at areas
needed or that happen to be coming up in propagation, there are a lot of
contests in which you still want to work people calling off the back of
your beam. Won't the big F/B be a liability in this situation?
In the olden days of DXing, a big F/B was probably a real asset when the DX
worked stations on his/her own frequency. Attenuating the shouting masses
(who never listen) would be a dream come true. But nowadays almost all the
really rare stuff is worked split. In this case, you want good copy on the
U.S. side of the QSO so you can pinpoint the DX listening frequency. Again,
a big F/B works against this.
So, would it be fair to say that the KT-34XA is a better antenna for
contesting and DXing than the TH7DX, and that the latter is better for
ragchewing and similar situations in which you want to exclude stations
behind your beam (i.e., reduce interference when ragchewing?)
Hope I don't start WWIII with this one...
73, Dick, WC1M
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