rickman wrote:
I just read the wikipedia article on small loop antennas and it seems I
was laboring under a misapprehension. I thought receiving loops were
"magnetic" because they were shielded (this is often stated in various
web pages about constructing such loops). But the wikipedia article on
small loop antennas says the nature of a small loop is to not be very
sensitive to the E field in near field.

So if the shield has little to do with rejecting near field electrical
noise, what does the shield do? A lot of antenna designs make a big
deal of the shield. So I assume it must be a useful addition to the
small loop antenna for some purpose.

The single-turn tuned magnetic loop as used for transmitting is a
different animal than the aperiodic loop of usually a couple of turns
that is used for receive-only applications.

The tuned loop cannot be shielded because of the parasitic capacitance
that would add, it would limit the high end of the tuning range.

Of course a shielded loop also will resonate at some frequency due to
parasitic capacitance.