Gary Schafer wrote:
. . .
The calibration points that Mike did on his receiver should be valid
for any band for his antenna comparisons. An actual signal strength
measurement is not required nor would it be valid between bands. All
that is really needed is the difference measurements between the two
antennas so his calibration between points on the meter scale will be
valid on any band.

I'm not sure I fully understand this. The difference from one S meter
division to another *is* likely to be different on different bands,
since it depends on the gain-vs-voltage characteristics of the
controlled stages which can vary with frequency. But I do agree that he
can make good comparative antenna measurements without good S meter
calibration, because he has a step attenuator. By simply setting the
attenuator so he gets the same S-meter reading on both antennas, S-meter
calibration is completely irrelevant -- the antenna gain difference is
the attenuator setting.

I find it useful, however, to be able to see the difference with
reasonable accuracy just by looking at my S meter. But that does require
calibration for the band in use.

. . .

Roy Lewallen, W7EL