Someone recently mentioned the Wellbrook loop.
I borrowed a Wellbrook loop for antenna comparisons a while back. Weak
signals on MF that i could copy with my 1/4 wave inv L on MF and also my 160m
inv L also used to RX on MF. I could not even hear these weak signals on the
Loop.
I could copy stronger signals on the Loop but these were 2 to 3 S units
down on the above wire antennas.
A vertical loop is not ideal for all round listening except it is
rotatable, but could be useful to null out noise at a noisy QTH
A resonated length of wire as long as possible would be a better choice
for all round listening
de G3KEV