I would not be quoting some ham¹s web site as an authority on
electromagnetic theory or folklore.

You might want to Google Tom W8JI and find out who he is. To describe one of
the U.S.'s brighter engineers and designers as "some ham" is a real
disservice. The fact that he happens to have a ham license is purely a
coincidence. His explaination of how the shielded loop functions is embraced
by the IEEE group on Electromagnetics and Propagation, Roy Lewellen (writer
of EZNEC software) et al.
W4OP