Improving AM reception with by Inductive coupling an antenna...

Here is another, this guy uses his big toe ?

I did a bunch of research into receiving loop antennas some time back and found the same sort of thing. For transmitting, loop designs tend to be much more calculated and a lot more energy is put into the planning. Often the coupling to the loop was inductive. While there are tons of information on the antenna design, there is very little available on the coupling loop. It seems that is often done by trial and error using other's experience as a guide for the starting point.

There are a couple of email groups for loop antenna design. snipped-for-privacy@groups.ioand snipped-for-privacy@groups.io. Go to the groups.io web site to find these groups. You will need to sign up, but this site is not evil in any way. In fact, it was started by some of the Yahoo groups designers who decided to go their own way. Then when Yahoo groups were removed, groups.io got a big boost.

Anyway, snipped-for-privacy@groups.io is very active and lots of good people there. Much more likely to get good info there than here. I know of one person here who is active in loop antenna design. He does some interesting stuff. I recall a few years back he was working on very high Q designs. Seems the limiting factor in the whole high Q thing is the tuning capacitor as they can be much lower Q than a good loop. I think his name is Mike. I'm sure he will chime in when he reads your posts.

Rick, thanks for that. Is this the group that you were talking about: "Helically Loaded Mag Loop" ?

No, that would seem to be a very specialize group. The groups I mentioned are exactly as I indicated. Wait, seems I managed to screw that up and gave you the same group twice. The other one, the much more active group, would be "loopantennas" You should be able to search groups.io for that keyword. Or here is the link.

OK, got it. Thanks for the help, I will post my message there. Thanks

Rick C., Your were correct. Lots of articles and help on that site. [

Sid.

There's a tutorial on the design of loop and capacitive antennas, and an equivalent circuit model, for AM reception in the National Audio Handbook:

Section 3-1, page 78 in the PDF.

For the effective height of an air core loop (the PDF only has ferrite loop approximation) it's here:

Two more useful links, page 23 on magnetically coupling to internal ferrite rod:

On loop sizing with respect to SNR for a given band:

Here's one of the better tutorials for your specific problem, improving AM reception:

This doesn't answer your question. It's just another neat example of unintended consequences. Slinky was invented because Richard James accidentally knocked a spring off of a work desk. I saw it on the A&E show, The Toys That Built America. They mentioned that it could be used as an antenna. His wife, Betty, chose the name.

On a sunny day (Wed, 16 Feb 2022 10:13:15 -0800 (PST)) it happened Dean Hoffman snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:

If you have enough space ... this is for 20 meters so you need a big tower for MW:

And if you get an antenna analyzer:

Plenty info on the internet, just google 'calculating loop antenna''