FAQs from Rohde & Schwarz

How to bisect the result in dB with Trace Mathematics


I want to measure the attenuation of a long cable by means of an S11 measurement.

The other end of the cable is terminated with a short.

I use the dB magnitude format, and what I see is the attenuation of two times the cable attenuation.

How can I bisect this result in dB with the Trace Mathematics?


In this context, we have to keep in mind that the following applies:

log(x) / 2 = log( x ^ 0.5)

When we take the square root of the linear magnitude and show this result in a dB magnitude, we have thus bisected the dB result.

So just do the following:

- Take the S11 measurement in dB Mag format as Trc1

- Add Trc2 with the same settings as Trc1

- Perform a User Def Math for Trc2 using the formula

linMag ( Trc1) ^ 0.5

- Switch the Math = User Def for Trc2 on