Ground-Level HF Beam Tuning?
kd5sak wrote:
.. . . .
Another local Ham and I have built two monoband 20 meter versions of the
HexBeam
utilizing info from W1GQLs hexbeam website (one with PVC spreaders and one
with fiberglass rod spreaders). Neither had to be adjusted at all after the
original wire length was cut.
Somebody did something right.
Mine has usable tuning at just above ground
level and it's expected to get only better with height, as the other one
did.
Without any noticeable resonant point or F/B ratio shifts??
Granted, we didn't have the other band elements to fuss with. If you
can get element lengths and vertical separation distances from someone with
a working multibander chances are you won't need to do any adjusting on
those, either.
I'm early into my education on building hexbeams and I've seen a bunch
of this type info published but have not yet dug very far ito it.
W1GQL has suggested, with the finite lifespan of such
antennas and the current lowpoint of the sunspot cycle, that there is no
overwhelming need for 10, 12, and 15 meter elements for at least the next
couple of years.
I don't particularly agree with that. This past weekend hi-band
conditions were below average for the current period but any number of
individual stations operating in the CQ DX CW contest logged hundreds
of 15M contacts each in dozens of countries. Their results on 10M were
dramatically down vs. their results on 15M but their results on 15M
were only down by maybe 20% compared with last year.
I've spent a lot of hours chasing DX on 15M thru a number of sunspot
lows. The biggest problem 15M has is that during the lows the
expectations are that the band is dead like 10M is dead and not worth
bothering with. So they don't. Which is their loss because any number
of times there are great openings on 15M but the few who do tune the
band are all listening instead of transmitting so of course the band
seems "dead". 15M is a gottahave here.
You might try building your antenna as a monoband 20 meter,
but construct the antenna with sufficient spreader tension and bow depth
that you can later add additional bands.
That's reasonable. After thinking about it 12/10M really are coming up
as complete losses so a 20/17/15M version would be a good compromise as
far as the payoffs for the investments in effort go.
The foregoing advice is free and
not necessarily valuable, but is given with friendly intent.(G)
.. . so are my questions (G).
My own
fiberglass HexBeam has a 30" bow depth and I may yet attempt to add a band
or two later. Good luck with yours however you choose to build it.
Thanks. I'll need it.
Harold
KD5SAK
Brian w3rv
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