Calculate transmission line Matched Line Loss from Rin of o/c or s/c resonant or antiresonant section

This calculator allows calculation of transmission line Matched Line Loss from Rin of open or shorted resonant or antiresonant line section (see Measuring matched line loss).

The results are valid only for linear circuits.

Rin (Ω):
Ro (or Zo):
Length (m):
MLL (dB/m):

The calculator does not do a lot of error checking, if you enter nonsense, it will probably produce nonsense.

The calculator solves \(MLL=\frac{-10}{length} log |\frac{Rin-Zo}{Rin+Zo}| \; dB/m\). The accuracy depends on the accuracy of Zo.Because of the Rin-Zo term, accuracy becomes very sensitive to errors in Zo when Rin approaches Zo. In practice, this does not normally limit the use of the technique at HF and above, if Rin approaches Zo, use a shorter resonant length that gives an Rin that you can measure reasonably accurately.

The response of Rin is quite broad for the low impedance resonance, but VERY sharp for the high impedance resonance (antiresonance) making it more difficult to find the true value of Rin as X crosses zero. So, whilst the calculator works correctly for high impedance resonances (antiresonances), make your measurements where ever possible at low impedance resonances as they will tend to have less error.

Some instruments work better for very low Z measurements which you may encounter, eg noise bridges, so always make the measurements for low Z resonances in that case.



Version Date Description
1.01 25/02/2016 Initial.

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