Grace, The latest version of EN 55022: 2006 allows 3-meter testing for some Class B devices. Otherwise, 10 meters is the accepted test distance. The assumption is often made that a device tested compliant at a 3-meter test distance will pass also at 10-meters. The allowed correlation is based on the theoretical inverse proportionality factor of 20 dB per decade. The actual correlation between 3-meter and 10-meter test distance has proven to be much more elusive. Bill
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Grace Lin Sent: Monday, June 18, 2007 12:43 PM To: [email protected] Subject: RE Measurement Distance per EU Dear Members, Is 3m measurement distance for radiated emission not accepted by EU? I propose a 3m full compliant chamber. A chamber manufacturer informs me that EU only accepts 10m measurement distance. I checked EN 55022: 1998 incorprating Corrigendum Nol 1 and A1 and A2. Clause 6 states: "The EUT shall meet the limits of Table 5 or Table 6 when measured at the measuring distance R in accordance with the methods described in Clause 10. ... " The title of Table 5 is: "Table 5 - Limits for radiated disturbance of class A ITE at a measuring distance of 10m". The title of Table 6 is: "Table 6 - Limits for radiated disturbanc eof class B ITE at a measuring distance of 10m". Subclause 10.2.1 states: " 10.2.1 Antenna-to-EUT distance Measurements of the radiated field shall be made with the antenna located at the horizontal distance from the boundary of the EUT as specified in Clasue 6. NOTE If the field-strength measurement at 10m cannot be made because of high ambient noise levels, or fo rother reasons, measurement of class B EUT's may be made at a closer distance, for example 3m. An inverse proportionality factor of 20 dB per decade should be used to normalize the measured data to the specified distance for determining compliance. Care should be taken in the measurement of large EUTs at 3m at frequencies near 30 MHz, due to near field effects. " I look forward to your comments. Best regards, Grace Lin Crestron Electronics, Inc. www.crestron.com - ---------------------------------------------------------------- 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 ______________________________________________________________________ - ---------------------------------------------------------------- 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
