Buck wrote:
. . .
He agrees that the antenna is better as it improves receive as well as
transmit, but I can't see the TOA being more important than the gain
unless it is really off by a long way. . .

It's important to realize that at HF (where atmospheric rather than
receiver noise dominates), different criteria are important for
receiving than transmitting antenna improvement.

If you simply increase the gain of an antenna without changing the
pattern (by, for example, improving the efficiency of a vertical by
adding more radials), it improves the S/N ratio at the station you're
talking to, but it doesn't help the S/N ratio at your end. The reason is
that both of you are getting noise from elsewhere. When you increase
your gain, it improves the signal at the other end, while the noise at
the other end stays the same, hence the S/N ratio improvement. But the
gain increase causes both the signal and the noise to increase at your
end, both in the same proportion. So you've improved your transmit
effectiveness but haven't improved your ability to receive. You've done
no more than you would by turning up the volume control.

The only way to improve your ability to receive at HF is to improve the
directivity of the antenna, so it has less gain in the direction the
noise, or some of the noise, is coming from compared to the direction of
the station you're talking with. Deep pattern nulls are usually an
important factor in doing this. If the signal and bulk of the noise both
come from the same direction, you're stuck. The pattern makes no
difference for transmitting, only the gain in a single direction. (I'll
ignore the possibility of multipath propagation or surface/sky wave
interference for this simplified explanation.) But for receiving, the
ability to have different gains in different directions is important.
Because the absolute gain isn't important, a small and inefficient but
rotatable antenna with some good nulls can be an excellent receiving
antenna.

At VHF/UHF, where the noise primarily comes from the receiver front end,
antenna gain helps the S/N ratio for both transmitting and receiving.

Roy Lewallen, W7EL