"Frank" wrote in message
news:wN4qd.217617$9b.158132@edtnps84...
I think S meters should be calibrated in dB uV/m, or at least dBm input.

Frank


You cannot do that. Even on a good meter (like a spectrum analyzer or an EMI
receiver), the meter is calibrated only for input power at its front panel
connector. You still have to add a frequency dependent correction factor for
cable loss and antenna efficiency. Very expensive measurement systems
operate under computer control, with a calibrated analyzer and the computer
adding the appropriate factors for cable loss and antenna factor. (This
allows for flexibility; a different coax or antenna can be substituted at
any time, so long as the computer has a table of factors for the new
device.)

As for how you mark the S-meter scale, I agree that we use an archaic system
with S-units. It would be more rational to use a simple dB scale referenced
to something like 1 picowatt (which would then become 0 dBpW). OTOH, the
purpose of an S-meter is not to provide absolute measurements. It is used as
a tuning indicator and for relative signal strength comparisons. And the
archaic marking system works fine for that need.

Ed
wb6wsn