James Moritz wrote:

G3LNP's design deliberately degrades
the Q to give a wider bandwidth, and eliminate the need for remote
tuning. Another reason why you might not want the highest possible
Q is that a high Q loop is more easily de-tuned, for example by rain
or movement.

My loop, which is matched via a capacitor divider network as described on my web
site, has a usable bandwidth of around 300Hz before retuning it is necessary.
But it is not effected by rain or movement (apart from in heavy winds when the
SWR jumps somewhat), the only environmental change is between hot and cold
weather when the value of the tuning caps changes - on a cold frosty morning it
is some 300Hz lower in frequency which rapidly moves the other way when the sun
starts to shine on the matching box!

I also spoke to Mike Underhill after his talk and he is certainly interested
with the work we are doing with loops on lf.  Results some of us have achieved
seem to indicate that conventional theory is too pessimistic and I look forward
to seeing his report in writing.  It seems Mike is not available via email.

Cheers Dave G3YMC
[email protected]
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http://ourworld.compuserve.com/homepages/sergeantd