From: Ben Bibb <[email protected]> Subject: Re: Pre-Compliance testing for radiated emissions using a current probe
At 12:28 PM 2/11/99 -0700, you wrote: >Hello Group, > >Some time ago (1996) in an email thread on absorbing clamps, Michael A. >Royer stated that CISPR 14 defines a method for using current clamps instead >of open area test sites. There was another thread for an on-site radiated >emissions test when in noisy environments that mentioned using clamp-on >probes. > >Additionally I recall and article in one of the trade magazines (Compliance >Engineering, ITEM, etc.) that described a method where a person could bundle >all of the service connections for a product into an RF current clamp-on >probe. The article also had information on converting the data on a >spectrum analyzer into equivalent open area test site numbers. > >I would like to perform a test like this but have been unable to find a >clamp-on probe that has at least a 100mm inner diameter and a frequency >range of 30 MHz to 1000 MHz, possibly this is limited by physics. > >Is there anyone out there who is able to point me to articles or websites >on: > >1) RF current probe manufacturers. >2) The article and/or mathematical algorithm on measuring radiated >emissions with current probe. >3) Application information. > >Thank you for any help you can provide. > >================================== >Doug Powell, Compliance Engineer >Advanced Energy Industries, Inc. >Fort Collins, Colorado USA > >[email protected] >www.advanced-energy.com >================================== > Hi Doug, You probably do not want to try to go to a GHz, 10 KHz through a couple of hundred MHz is a good starting point. Around 300 to 500 MHz probes get pretty tricky. The serious BCI standards stop at 400 or 500 MHz. The Current :: OATS correlation works very well if you are careful to explain all the paths. You could even construct and calibrate your own probes. We have found good correlation to the 10m OATS below 200 MHz, remember cables do not work as well as slots or other types of EMC "antennas" above a hundred or so MHz. (1) Fischer Custom Controls, http://www.fischercc.com makes excellent probes. EMC Test Systems, http://emctest.com also makes the Tegam probe line. (2) A basic EMC text. "EMC For Product Designers", Tim Williams, ISBN 0 7506 1264 9. My favorite. "Introduction to Electromagnetic Compatibility", C. R. Paul ISBNISBN 0-471-54927-4 (3) See (1) above. They will have apps stuff. If you can't find the math in an EMC text book you have, contact me direct, I will get you going. Regards, Ben Bibb, NCE LambdaMetrics, Inc. NIST/NVLAP Accredited EMC and Telecom Lab. PO Box 1029 Cedar Park, Texas, 78630-1029 http://www.lambdametrics.com (512) 219-8218 Voice and Auto-fax
