Thanks for your comments. Do you believe there is any technical basis for
claims that vertical antennas are noisier than horizontal antennas due to
more man made noise being created with vertical polarization? This makes
inverted V an ideal compromise?


Things to consider:

Vertical antenna is "looking" at signals close to ground and at vertical
polarization.

Most of the local noise (fluorescent lights, noisy dimmers, etc.) is "all"
polarized but when in the "view" of the antenna, it will be significantly
stronger.

Horizontal antenna might just "look" over it or when oriented with null in
the pattern at the noise source, "ignore" it.

In the case of 160m vs. 40m dipole less noise case, it could be also that
the ends (and rest of the antenna) of the 40m dipole are farther away from
the local noise source and with mismatch could give improved S/N reception.

With atmospheric noise, the best remedy is the directional array that
reduces the amount of the degrees of noise from undesired directions.
Equatorial noise is major culprit.

Good tool to fight noise is the noise limiter - phasing unit.

73 Yuri, www.K3BU.us