The 2003 and 2009 editions of ANSI C63.4 have recently been recognized by the FCC in a Public Notice issued in November for compliance measurements for product certification. In the 2009 edition, there are two methods for site validation above 1 GHz. One is to have absorber laid down in a particular pattern between the place where the EUT is placed and the measurement antenna location. The absorbers have to have a specific performance identified in the 2009 edition. The second method in making site validation measurements is to use the method in IEC/CISPR in their publication 16-1-4. This is referred to as the site VSWR method (S-VSWR). This is based on a series of measurements at the extremes of the EUT volume occupied on the test site using a specified transmit and receiving antennas aimed at each other and test equipment owned by every test laboratory. This work was based on years of effort that included practical experimentation by several test labs. Presently test site validation is performed using this technique internationally.
In ASC C63®, work has been proceeding in another method that has much promise as indicated in this article. This is part of the work that will lead to the publication C63.25. It has been shown that using this time domain approach will add value in that it not only will determine if a site meets validation requirement but also locate areas in the test site where the site may need to be improved or rid itself of a reflective source to meet the site validation requirement using this technique. To facilitate this test, a vector network analyzer is needed which may not be available to a test lab but can be rented for the purpose. Experimentation with this technique has been ongoing with test labs showing its usefulness. Preliminary results that both the S-VSWR and time domain techniques have given similar site validation results, i.e. sites meet the acceptance criteria for both validation techniques. This is quite helpful as the test lab does not want to perform two validation techniques to show site acceptance. Once there is experience with the time domain technique, it should be considered for introduction into C63.4 or referenced as one of the options for site validation above 1 GHz.
CISPR has been introduced to time domain concept in the past. The work on the S-VSWR received the immediate attention and hence was published. ASC C63® is encouraged to suggest time domain site validation techniques to CISPR as a US contribution. The best time for this is once C63.25 is published; it is always preferable to base inputs to CISPR on published standards that are used by industry. This will show the usefulness and practical application for test labs. Such usefulness is also a goal of CISPR as it provides basic standards covering measurement methods and instrumentation (including test sites). Hence, the users of C63.25 when it is published will be encouraged to bring the matter to the attention of members of the technical advisory committee of the US National Committee of the IEC/CISPR. All inputs to the CISPR must come from a member of the working group for in this case, CISPR Subcommittee A Working Group 1. While this concept has been discussed, it is time again to revisit it with the CISPR working group by tabling a document for consideration at the WG’s next meeting in Seattle in October 2010.
This then leads to a call for help in working with the new technique and the drafting of C63.25 as well as introducing it into the CISPR working group noted above. Please contact
Don Heirman at email@example.com if there are questions on your willingness to work this exciting project(s).
Donald Heirman is president of Don HEIRMAN Consultants, training, standards, and educational electromagnetic compatibility (EMC) consultation corporation. Previously he was with Bell Laboratories for over 30 years in many EMC roles including Manager of Lucent Technologies (Bell Labs) Global Product Compliance Laboratory, which he founded, and where he was in charge of the Corporation’s major EMC and regulatory test facility and its participation in ANSI accredited standards and international EMC standardization committees. He chairs, or is a principal technical contributor to, US and international EMC standards organizations including ANSI ASC C63® (chairman) and the International Electrotechnical Commission’s (IEC) Special International Committee on Radio Interference (CISPR) where in October 2007 he was named the chair of CISPR moving from his previous role as its subcommittee A chairman responsible for CISPR Publication 16 on basic EMC measurement methods, test instrumentation requirements and statistical methods. He is a member of the IEC’s Advisory Committee on EMC (ACEC) and the Technical Management Committee of the US National Committee of the IEC. In November 2008 he was presented with the prestigious IEC Lord Kelvin award at the IEC General Meeting in Sao Paulo, Brazil. He is a life Fellow of the IEEE and a life member of the IEEE EMC Society (EMCS) and member of its Board of Directors, chair of its technical committee on EMC measurements, past EMCS president and vice president for standards, and past chair of its standards development committee. He also is past president of the IEEE Standards Association and past member of the IEEE Board of Directors.