I have a new SteppIR antenna to play with and I noticed an odd response. If
I set the beam for 17 or 15 meters but listen on 20 meters I seem to have a
better S/N ratio on signals. If I then switch the beam to 20 meters (while
continuing to listen on 20) the background noise and the signals go up but
the noise goes up more than the signals.

Expressed another way, is a non-resonant antenna sometimes better for
reception than a resonant antenna?

This may be a well-known effect, but it is new to me.

Bill
W2WO