That's a very interesting write up David.
Buzz, how close is your circuit to Wellbrook's? Is the circuit of the Wellbrook loop known? I assumed it was a commercial secret - or at least the more subtle aspects of the design - although I expect the Wellbrook loop to follow conventional loop antenna design.
However, Wellbrook Communications have made various changes and improvements over the years and it would be great to see a head-to-head comparison with the clone both in technical measurements and real-life performance.
For info:
https://www.wellbrook.uk.com/loopantennas/Loop_Antennas