# Lost & Found

Some random electronics related stuff that you may find useful. Will be expanded continuously.

• ### A dBm conversion table

A table to convert between dBm, power, and voltage in 50 Ω systems. From −130 dBm to +30 dBm. Print it out and pin it up at your bench. The table is in pdf format. Created with a GNU Octave script and LaTeX.

• ### Nomogram for uncertainty in return loss measurements

Gives the worst case upper and lower uncertainty bounds in a return loss measurement due to an adapter of specified return loss between DUT and directional coupler (or measuring bridge). Also applies if the directivity of the directional coupler is used in place of the return loss of the adapter. Here is another version with different scaling. Generated by this script for GNU Octave.
Example: A DUT with a return loss of 30 dB is measured through an adapter with a return loss of 40 dB (or with a directional coupler with 40 dB directivity). Then the uncertainty bounds of the measurement are read off to be $30\,{\rm dB}+2.4\,{\rm dB}$ and $30\,{\rm dB}-3.3\,{\rm dB}$.

• ### An Octave script for evaluating parametric models of OSM calibration kits

This GNU Octave script evaluates the standard parametric model for the open and short standard of an OSM calibration kit. It prints the result as a polar plot and generates two Touchstone (.s1p) files containing the S11-data obtained from the model. Modify the parameters in the script for your cal standards and specify the start and stop frequency as well as the number of data points required (see the comments). The model specification follows the Keysight convention (Application Note 5989-4840EN).