In a message dated 10/25/01 5:13:01 AM Pacific Daylight Time,
RCARIELLO@si.rr.com writes:<<
Hello,
With all this talk about vertical antennas let me ask this question.
I have been told that a crankup tower will not load well as a vertical do to
the sections not being fastened together.
My thought would be to hang wires along the side of the tower similar to a
cage dipole with the tower inside. These wires would be spaced and insolated
from the tower. At the top the wires would be joined together. At the base a
ring going around the tower where all the hanging wires would be
attached.This cage of wires would be insolated from ground. Along the tower
spacers or rings might be used to prevent the hanging wires from hitting
and shorting to the tower. To extend the height of the tower a vertical
element could be attached to the wires but insolated from the tower.
Comments please.
Rich AA2MF
aa2mf@arrl.net
>>
Rich: This is a good idea and depending on how you do it, it can be used to
obtain a real high feedpoint Z also. Or for starters just do this. Connect
a insulated wire or 2 to the top of the tower and to the bottom of the tower.
It's just a low resistance path parallel that doesn't change resistance next
to the tower. Try that first for a reference and then do the cage
construction around the tower which can give a couple of variations and it
will increase the bandwidth. As I just said in a previous post yesterday,
I've not seen anyone suggest using a cage construction in over 40 years.
Well you finally did!
I had planned a similiar construction for a 160m vertical that would give a
600 ohm feedpoint for 600 ohm open wire line on the far end of my property.
It would feed right into a link coupled tank circuit of my old Pr 813's final
with the right nuimber of turns with a series Xc. That's about as efficient
and broadbanded as one can get with a feed system. We didn't have bandwidth
problems even on 160M before coax and all it's balun problems. That's the way
it was done in the Stone Age of the Last Century and it has never ever been
improved upon. The convenience of coax and the bandswitching 50 ohm Pi
network of Art Collins in the 32V series and KW-1 was a step backwards in
efficiency and bandwidth. It is better than the 50 ohm output rigs. It has
it's applications that I use myself but not for top monoband operations of a
competitive nature.
If your tower was a 1/2 wave, the feedpont Z of the cage construction would
be perhaps around 4000 ohms +/-. It can be adjusted to a wide range of Z's
even lower. At the end of an odd multiple of 1/4 waves of very low loss 450
ohm line you can make, it will give you 50 ohms balanced. There are all
kinds of combos on each end to get what ever Z you want.
It appears to me from my comparisons and success with 1/2 waves with and
without ground systems, the E field loss of a 1/2 wave in the local area is
less than the H field loss from 1/4 waves with limited radials. A 1/2 wave
being already resonant lends itself to a fairly short radial system more than
does a 1/4 wave when space doesn't permit a full 1/4 wave radial system. The
high current meat section of a 1/2 wave is a 1/4 wave above ground. I will
do a side by side comparsion this winter.
Since the finances of the average DXer are higher than ever, I cannot see
this slavery to 1/4 wave verticals even on 160M and all this radial dialog of
one senairo after another that never gets solved or agreed upon. A lot of
these problems "just go away" when you use 1/2 waves. However I've seen that
the great patterns of a 4 Square don't duplicate with 1/2 or 5/8 waves. One
would have thought the vertical patterns would have really flattened out.
I'm working on 4 Square type and other configurations using 1/2&5/8 wave
verticals. Keep in touch.
Rich: Congratulations for one of the good new ideas we don't see enough of on
TT. Ignore those who say it won't work without trying it. That's why so few
are
presented.
You get the
"K7GCO New & Creative Idea of the Year Award "
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