"Quantum Receiver".

[synchro1]

Would it be better to use a higher diameter for the coil, and less turns ?The highest Q is achieved by using only 1 turn of very thick copper (magnetic loop antenna).Those antennas have a very high Q.
Or maybe a flat coil with only a few windings, like Tesla used ?

This L-3 coil is I/2 of a short wave radio transmitter resonating tuner circuit tank. It is tuned to receive a power broadcast from Space. It's no different from a normal short wave radio transmitting or receiving coil. Does yours work?

[skywatcher]

There are also commercial 13.56 MHz antennas available, for RFID applications, like this one: 

https://www.alibaba.com/product-detail/Free-Sample-Long-Range-PET-13_60597153218.html


I wonder why nobody detected any strange effects with this frequency, when it is so widely used in the industry.

[synchro1]

There are also commercial 13.56 MHz antennas available, for RFID applications, like this one: 

https://www.alibaba.com/product-detail/Free-Sample-Long-Range-PET-13_60597153218.html


I wonder why nobody detected any strange effects with this frequency, when it is so widely used in the industry.

Go ahead and buy a bunch of those. They're only 12 cents! I don't see any reason why they wouldn't work. That would really be something! The wire gauge is diaphanous though.

[synchro1]

Here's a thicker gauge variety of spiral:

https://www.aliexpress.com/i/32859268160.html

[skywatcher]

Here's a thicker gauge variety of spiral:

https://www.aliexpress.com/i/32859268160.html

I doubt those have a SRF of 13.56 MHz... with only 20mm diameter and only a few turns.

I now have 2 identical coils (like the yellow one i previously showed) and both have SRF of 13.44 MHz. That's as close as i can get.