Cecil Moore wrote:
The formula for theoretical TOTAL losses in a *resonant* stub:

Total loss = 10*log{[(Z0-R)/(Z0+R)]^2}

where R is the measured resistance of the resonant stub and Z0
is the characteristic impedance of the stub material. You can
see the [(Z0-R)/(Z0+R)]^2 term is akin to a virtual rho^2 at
the mouth of the stub. Since rho^2 = Pref/Pfor, the losses in
the stub are equivalent to the losses in an equivalent resistance
equal to the measured virtual resistance at the mouth of the stub.

In other words, replace the stub with a resistor having the same
value of measured resistance as the stub, and calculate the I^2*R
losses in the resistor. That will be the same value as the total
losses in the stub.
--
73, Cecil http://www.qsl.net/w5dxp