Topband: comparing a vertical to a horizontal loop

[Carl Luetzelschwab]

Bill VE3CSK said "I have been listening several evenings now on 160M using
my K3 in diversity mode with the TX vertical array on one receiver and a
full-wave horizontal loop on the other. The rapid apparent polarization
shifts seemed quite different from the slower QSB that we often experience
on 160."

How do you know it's polarization and not elevation angle?

Carl K9LA.