Brian, I prefer running the test the way you describe, for better repeatability. However, the standard test setup includes a 6dB attenuator at the input of the EM clamp (or CDN) and the resulting increase in the return loss due to the attenuator would tend to mask some of the effect of EUT impedance change, would it not? I've always wondered about that same effect from radiated tests with an antenna balun that is not efficient, just how accurate would the reflected power reading be with a crappy antenna balun and non-resonant antenna? (like most of the hybrid antennas at 26 MHz) :-) Bob Richards, NCT.
"Kunde, Brian" <[email protected]> wrote: Bob, Can a directional coupler be used between the amp and the clamp to measure the forward power during the calibration test, then with the clamp connected to the EUT, re-level on your calibration points to match the forward power? Would this compensate for the impedance difference in the EUT? This is a similar method used for radiated immunity to adjust for impedance differences between the antenna and the field affected by the EUT. The Other Brian - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
