Evaluation Engineering - December 2008 - (Page 48)

EMC TEST • No corrections are applied to the calibration results (NFSAF) for broadband antennas such as the log periodic used for product testing. This is the same as previous versions of the standard. • GSCFs for broadband antennas such as the log periodic dipole arrays are measured in all geometries required for NSA measurements at 3- and 10-meter separation. This is similar to previous versions of the standard. There are more restrictions on the site that will be used for measuring GSCF. In addition, several measurements over different parts of the ground plane are needed for each geometry. • Broadband horn antennas may be calibrated using the SSM with the exception that height search is not necessary when there is no ground reﬂection. Although this is not new, very few people are aware of this FSAF measurement option. statement. For exact details, refer to ANSI C63.5-2006 5.2 pages 10-11. References/Additional Reading • ANSI C63.4-2003: Methods of Measurement of Radio-Noise Emissions from Low-Voltage Electrical and Electronic Equipment in the Range of 9 kHz to 40 GHz • CISPR 16-1-5: Speciﬁcation for radio disturbance and immunity measuring apparatus and methods—Antenna calibration test sites for 30 MHz to 1,000 MHz, November 2003 • ANSI C63.5- 2006: Electromagnetic Compatibility–Radiated Emission Measurements in Electromagnetic Interference (EMI) Control–Calibration of Antennas (9 kHz to 40 GHz) • SAE/ARP 958-2003 Aerospace Recommended Practice: Electromagnetic Interference Measurement Antennas; Standard Calibration Method 2009 ANSI C63.5 Workshop The ANSI C63.5 Workshop, scheduled in conjunction with the 2009 IEEE International Symposium on EMC, will feature a series of lectures on ANSI C63.5 by Don Heirman, chair of the ANSI ASC C63® Committee; Mike Windler of Underwriters Laboratories, chair of ANSI ASC C63® Subcommittee 1 where this standard resides; and Dennis Camell of NIST, chair of the working group addressing revisions to the standard. Following the lectures, hands-on demonstrations will supplement the material presented using the ISO 17205-certiﬁed OATS and A2LAaccredited lab at ETS-Lindgren. Summary Accurate and repeatable antenna calibration is becoming increasingly important as antenna technology has advanced. Revisions to ANSI C63.5 are taking into account new impact factors such as measurement uncertainties and new technology developments such as seen with the log periodic, biconical, and horn antenna types. Bottom line, the antenna is the ﬁrst piece of a radiated emissions measurement system, and its impact on test results cannot be understated. Accordingly, proper and timely antenna calibration is essential to maintaining the optimal measurement system. While the changes incorporated in ANSI C63.5-2006 have had a signiﬁcant effect on biconical antenna calibrations used for product testing and site validation, they have removed 3-meter calibrations for most antennas and eliminated references to vertical calibrations. Remember, calibration providers are an excellent resource for information, but you know your business best. Always ensure that you are up to date and request the test that ﬁts your requirements and be very speciﬁc about the calibration that you are purchasing and that the calibration standard is speciﬁed. Acknowledgement The author would like to thank key contributors to this article: Mike Windler and Bob DeLisi of Underwriters Laboratories and Zhong Chen of ETS-Lindgren for reviewing the article and Don Heirman, chair of ASC C63 ®, for reviewing and providing further background material on the efforts in ASC C63® and its relation to CISPR activity. The changes have removed 3-meter calibrations for most antennas and eliminated references to vertical calibrations. Usage Options Since the 3-meter calibration has been removed from ANSI C63.5, for most antennas you still can have the calibration performed under SAE/ARP 958. Although this is known for 1-meter calibrations, Annex C provides the same method for determining antenna factors at 3 meters that was previously in ANSI C63.5. If you are conducting testing per ANSI C63.4, you must use the antenna factors derived from calibrations as specified in ANSI C63.5. It is your responsibility to specify the calibration to be performed. Horn antennas may be calibrated at a distance of less than 10 meters, but the antenna factors can only be used at that distance. This is a very simpliﬁed 4 8 • E E • December 2008 About the Author Ron Bethel is the calibration manager for ETS-Lindgren. He has been employed by the company for more than 12 years. ETS-Lindgren, 1301 Arrow Point Dr., Cedar Park, TX 78613, e-mail: ron.bethel@ets-lindgren.com FOR MORE INFORMATION on the ASC C63® standard and its status enter this rsleads URL www.rsleads.com/812ee-218 on the ASC C63® Workshop enter this rsleads URL www.rsleads.com/812ee-219 on the 2009 EMC Symposium enter this rsleads URL www.rsleads.com/812ee-220 www.e v alu a ti o n e n g i n e e r i n g . co m al u co http://www.rsleads.com/812ee-218 http://www.rsleads.com/812ee-219 http://www.rsleads.com/812ee-220 http://www.evaluationengineering.com

Table of Contents Feed for the Digital Edition of Evaluation Engineering - December 2008

Evaluation Engineering - December 2008 Contents Editorial Product Briefing Test Software C-V Measurements Nanoelectronics Test Product Guide Company Guide Machine Vision EMC Test Index of Advertisers

Evaluation Engineering - December 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.