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Twin
wires giving more gain
By Andy Ikin
K9AY web group, October 2, 2000
I have been experimenting with some loop configurations suggested
by Johan Bodin a few months ago.
Without going into lengthy detail, one configuration consisted of
two loops mounted at right angles connected in series.
To my surprise I measured a 5/6dB increase in gain over the normal
K9AY config. As a co-incidence, an e-mail from Gary was forward
to me, giving details of a 6dB increase gain using a two turn loop
with a resistive plus reactive termination.
Therefore, I had to see if a single loop of two turns would work
for LW and MW with just resistive termination.
Well as far as I can see, the answer is yes, but only if the turns
are separated to reduce mutual coupling, i.e. using a twin lead
wire loop connect in series only provides about a 2 dB gain increase.
Separating the delta loops by 1m at each end of the loop i.e. two
poles at each end. The loops cross at the apex. This provided the
5/6dB gain increase.
The only reason I can explain for this increase in gain is that
the 450-50 match xmfr is not optimised for LW/MW. Hence raising
the antenna impedance with two turn loop provides a better match!
So the experimentation continues.
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