Has anybody had any experience shuntfeeding towers for 160M.
I'm looking for information to shunt feed 2 100 foot towers and then phase the two towers together.


thanks

Gerry
ve6qlt

Has anybody had any experience shuntfeeding towers for 160M.
I'm looking for information to shunt feed 2 100 foot towers and then =
phase the two towers together.



Get "ON4UN Low Band DXing" book, it is full of ideas, examples, phasing
systems.
Also check the TopBand reflector archives, lotsa stuff there too.

Yuri, K3BU

Gerry ..

Since the 100 foot mark is shorter than the quarter wave you'd like to
have, you have to think along two lines here. The first is that
whatever is mounted up at the top of the tower in the way of beams ans
so on forms a capacity hat. That has the effect of making the tower
look longer. It may be that your particular metal work will appear
longer than the desired quarter way, or .. if you are superbly lucky, a
perfect length. In that case, the idea of a shunt feed is likely to be
about what you would find in ON4UN's book or any antenna book on this
stuff in relation to broadcase band towers and so on.


The second line of thinking is a little different. Suppose whatever is
up there, if anything, on these 100 foot towers, is so small it presents
very little help for a capacity hat effect attempt. There is another
out, perhaps. You can then step away from the tower side with a yard
arm of a few feet or so. Then you drop a wire down the side off it to
ground. You feed that wire as a folded monopole to reasonate the whole
thing as a long thin loop sort of affair. Assuming that the tower guys
are insulated from the tower, there will perhaps be some point up that
tower where you can tap off with the yard arm and wire which forms the
loop which will reasonate on 160 as a folded monopole affair. If so,
you have your radiating element for which you are seeking.


LIkely, for this stuff, this is a cut and try issue! Suggestions have
been made in a number of articles as to this over the years. But the
only way you will really get it done, sad to say, is ... cut and try.
The only one I ever did like this was done with one man up the tower
with the yard arm for test, one on the ground with an antenna analyser
playing with the match. It was done before the current round of antenna
programs for computers. Obviously, if you want to work with one of
these programs and craft in all the segments and so on, it would be
likely that you'd get close to your particular configuration that way.
But in any case, if those two towers are loaded with different stuff up
at the top, it is going to be a different setup, to whatever extent they
are different, to get you radiating elements.


From the point where you have those two towers presenting, say, a 50
ohm match to a feed point for each, you can then take a look at the
spacing and begin to contemplate the phase delay which might give you a
pattern boost and/or rejection in a couple of directions you will get
based on where they are currently postured. That done you will
hopefully get where you want to go for the array.


Just thoughts for your consideration.


W5WQN



Gerry MacDonald wrote:

Has anybody had any experience shuntfeeding towers for 160M.
I'm looking for information to shunt feed 2 100 foot towers and then
phase the two towers together.


thanks

Gerry
ve6qlt



--


-- Sleep well; OS2's still awake!

Mike Luther