Bob, VE7HS wrote:
"I had an 80 metre loop some years ago, in a noisy urban enviroment, and
had the opposite experience, which is why I was interested in trying
it."

According to Bill Orr, W6SAI in "All About Cubical Quad Antennas" the
full-wave loop produces a power gain of about 1.4 dB over the 1/2-wave
dipole and its feedpoint impedance is about 125 ohms when the center of
the loop is about 0.65 wavelengths above the earth.

Take off paterns depend on soil, polarization, and height. ON4UN does a
good job with charts, graphs, and illustrations in his chapter on "Large
Loop Antennas" in "Low-Band DXing".

When the loop is vertically polarized over good soil, and the center of
the loop is 0.17 wavelengths above the earth, the elevation angle peaks
about 21 degrees above the horizon.

Best regards, Richard Harrison, KB5WZI