On 7/21/2011 12:09 PM, Dave Platt wrote:
In ,
wrote:

Hello 1st post here.

I have made 20 meter delta loop.
What I am thinking is...
If I also make a 40 meter loop, and a 10 meter loop, putting them either
side of the 20 loop. As in the 20 loop in the middle. The 40 behind, the 10
in front.
With suitable spacing, all strung on 3 fishing poles.
Will this work as a directional beam of sorts hopefully all 3 bands.
I am hoping 3 traditional elements on 20,
even driven element on 40 /with 2 directors,
and on 10 with 2 reflectors.
I know the lengths of the director's and reflectors won't be as standard but
with a tuner does anyone will it work to a degree?

I think you'd need to model it out with NEC to see if it would work.

I'm unclear as to whether you're planning to have separate feedlines
for the three delta loops, or whether you were thinking of just
driving one of the loops on all three bands and having the other two
loops be entirely passive. If you are thinking of driving the three
loops separately, I'm uncertain what you intend to do with the other
two loops - leave the feedlines open, short the feedlines, or
disconnect the loops from the feedlines and short the loops closed at
the feedpoint.



You'll be facing a few significant issues, when trying to use the
un-driven loops as directors / reflectors. For the sake of simplicity
I'll assume that the un-driven loops will be purely passive loops of
the expected length (e.g. no feedlines, or with the loop shorted
closed at the feedpoint).


There's another option: use some nested passive delta loops. Mount a
second 10-meter delta loop (tuned a bit lower in frequency than you
normally operate) suspended inside the 20-meter delta. Mount a second
20-meter loop (again, tuned a bit on the low side) inside the 40-meter
delta. This would give you the effect of a two-element beam (radiator
and reflector) on 10 and 20 meters, without affecting 40-meter
operation significantly.



Hard to know exactly what you're planning on building. Are you going to
have 3 loops, one for 10, one for 20, one for 40 arranged in a row, sort
of like rings on a post?

If you had a tuner on each loop, one might be able to get it to work.
For instance, one can build a Yagi with 3 equal (or arbitrary) length
elements and use L or C at the centers of the elements to get the
phasing right.

The problem with 3 loops of radically different size is that the L
and/or C might be impractically large/small to get it to work.

With a bit of work modeling, you MIGHT be able to come up with a single
L and C per band for each element, so you could use some sort of simple
"two relays per loop" scheme.