"Owen Duffy" wrote
I am more interested to hear from someone who says it can't be done,
what they tried that didn't work.

===================================
Owen,

I cannot but agree with everything you say and am inclined to say it
can't be done automatically with anywhere near to the required degree
of accuracy.

The obvious automatic way of tuning the loop is to use a remotely
controlled signal generator at the other end of the back yard and tune
up for maximum signal on receive. This should not be very difficult to
arrange but it is too uneconomic to be practical.

So I'll stick to manual tuning.

But I hasten to add that I hope this conversation does not deter
anybody from experimenting with magloops because magloops are, by far,
the most power-efficient of all the small, space-saving,
neighbor-friendly antennas.

Try one on the 160, 80 and 40 meter bands. At higher frequencies
there's usually enough space to erect a dipole or an inverted-L which
will perform at least as well. (Ian, you could perhaps do a useful
article on the subject.)

For the basic design, download program MAGLOOP4 from the website
below.
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

On Mon, 10 Oct 2005 11:33:48 +0000 (UTC), "Reg Edwards"
wrote:

....
At higher frequencies
there's usually enough space to erect a dipole or an inverted-L which
will perform at least as well. (Ian, you could perhaps do a useful
article on the subject.)

....

I wrote an article on the Inverted L with a remote autotuner (designed
for end-fed wires) some time ago. The configuration, it is frequency
agile, very convenient when integrated with transeiver auto-tune
controls, and works a treat. The most significant downside (like most
Marconi, Windom, Long Wire etc configs) is from an EMR safety point of
view, it has a radiator within reach of people standing on the ground.
The article is at
http://www.vk1od.net/InvertedL/InvertedL.htm .

With the experience of using such a configuration, I reckon that a
magloop with an remote autotuner designed specifically for a magloop
would be a great option for people with very little space, better than
Echolink!

Reg, if you have an expression for the loop inductance and resistance
as a function of frequency, and we could make the assumption that the
coupling coil is a broadband ideal transformer with a fixed z ratio or
otherwise characterise the transformation as a function of frequency,
I could do a software simulation of an autotuner... be an interesting
project.

BTW, the tuner values in the article above are found through
simulation of an automated L tuner, but the 3 variable binary
searching algorithm used for performance would not work for a loop.

Owen
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