I read in !emc-pstc that Chris Maxwell <chris.maxw...@nettest.com> wrote (in <83d652574e7af740873674f9fc12dbaaf7e...@utexh1w2.gnnettest.com>) about 'EN55022:1998 + A1:2000' on Wed, 29 Jan 2003:
>If the standard is assuming a 50 Ohm system, doesn't this breakdown to a simple >calculation? Quite possibly, but it *isn't* a 50 ohm system. The device should absorb the energy passing down the cable, not reflect it, so it should match the impedance of the cable/ground propagator well. This propagator has traditionally been assumed to have a characteristic impedance of 150 ohms. In an earlier post, I said that the transfer attenuation is 'irrelevant', and it escaped before I could correct it. It wouldn't be irrelevant if it were 3 dB, say, because that would mean that only half the energy was absorbed. So, it would be fairer to say that the attenuation is 'of secondary importance' compared with the input impedance, because if the impedance is far out, the energy never gets into the device, so can't be absorbed. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
