Harry Gaul reports that the January 2008 meeting was hosted by General Dynamics AIS at their Arizona Space Center Manufacturing Facility in Gilbert. Thirty-five people enjoyed the barbeque dinner and then listened to presentations on EMC design and testing of satellites by General Dynamics EMC Engineers, Glen Gassaway and Brian Daniel. Glen explained the history on the development of their state-of-the-art EMC test chamber where they test everything from box level to subsystem level to actual spacecrafts at the system level. Efficiency in testing is especially important because of the critical timelines in space programs. Glen mentioned that any delay in the testing of a spacecraft will translate to a cost of $100,000 per day. One technique to quickly assess the EMC of a spacecraft is to connect the output of on-board antennas directly to a spectrum analyzer in order to determine if there are any in-band unintentional emissions present. Brian Daniel outlined the engineering aspects of satellite development including the definition of test limits with special tailoring for receiver notches. Generally, vehicle compatibility while in orbit is the biggest concern although one must also consider the high RF levels that are present at the launch site. Brian said that 10% to 15% of a space vehicle’s weight can be attributed to the copper wiring. Cables are typically shielded by wrapping mesh tape around them. Following the presentations, the attendees were escorted on a tour of the facility including the EMC test chamber that measures 27 feet by 30 feet by 21 feet high. This chamber is equipped with a 14 foot wide by 20 foot high mechanized sliding door plug that enables test articles to be rolled into the chamber over a smooth level entry. This facility not only supports in-house work but it is also available for outside business. Information on future meetings is available on the Phoenix EMC Chapter Web site at http://www.ewh.ieee.org/r6/phoenix/phoenixemc/.
The Phoenix Chapter enjoyed a tour of the
EMI/EMC Laboratory at General Dynamics AIS in Gilbert, AZ. This facility
was built in 2004 and has already been used to test six space satellites.
The fall meeting of the IEEE EMC Phoenix Chapter meeting was held on November 7, 2007 at Garcia’s Mexican Restaurant, in the Embassy Suites Hotel at Rural Road and I-60 in Tempe, AZ. The meeting began with the customary social hour starting at 5:30 pm, with dinner at six. After we all had our fill of Garcia’s excellent food, Harry Gaul, our chapter chairman, called the meeting to order at 7:00 pm. The first order of business was the election of chapter officers for the new season. After some discussion and an informal vote, the chapter decided to retain the existing officers for another year. Harry then put out a call for speakers. Anyone that knows of an interesting and informative speaker that can present at the next chapter meeting should contact Harry or one of the other officers. Chapter business concluded with round table introductions and a call for EMC employment/employers.
Harry then introduced our featured speaker, Joe Butler of Chomerics. Joe currently has the dual roles of New Business Development Manager and Conductive Elastomers and Compounds Product Development Manager at Chomerics. He has over 35 years experience as an electromagnetic compatibility engineer. He is a senior life member and Past-President of the IEEE EMC Society and is also a past member of the IEEE EMCS Standards Committee. He is a NARTE certified EMC engineer and is a past member of the Board of Directors of NARTE. Joe has a BS in Engineering Physics from Merrimack College, an MA in Physics from Williams College, and an MBA from Northeastern University.
Joe started his presentation on shielding effectiveness testing of EMI shielding materials (such as EMI gaskets, paints, shielded windows and vents) by mentioning that the industry does not have a consensus standard in place. Rather, the test methods for shielding effectiveness range from variants of the long ago retired MIL-STD-285 to the more recent IEEE-STD-299. For military oriented products, the shielding data is quite often a result of a modified MIL-DTL-83528 test method. Although Joe described several shielding test methods for various products from various sources, the majority of shielding effectiveness data tends to be derived from radiated field testing methods. While many large corporations that have EMC groups on staff may use transfer impedance and reverberation chamber test methods due to their more inherent accuracy and repeatability, most vendors of shielding components have not followed their lead. The reasons for this difference in approach run from factors such as lack of resources, the comfort level of the vendor EMC engineers in interpreting the internally generated data, to the inherent frequency limitations of these latter test techniques when contrasted against the market need for 30 MHz to 40 GHz shielding effectiveness test data needed to market the products.
Current standards activities include revisions to IEEE-STD-299, generally creating three methods based on enclosure size. These activities are trending more towards reverberation chamber techniques, generally thought of as the most accurate. Unfortunately, these techniques may generate test data that makes shielding products look 'worse' than presently-used methods. For this reason, as well as cost and resources, most shielding manufacturers have not yet incorporated reverberation techniques as part of their material test programs.
Joe mentioned that some customers have recently been interested in assurances of long-term reliability through post environmental testing (such as ALT). The industry is also interested in 94V-0 flammability ratings, RoHS and other “green” initiatives. Customers have requested elemental analyses of various products. Material shielding effectiveness using modern trivalent coatings (MIL-C-5541F) has also been an issue. Some agree that new standards are needed for these trivalent coating techniques.
After the presentation, Harry Gaul presented Joe with a beautiful Arizona Highways Calendar for his excellent presentation. We would very much like to thank Joe Butler for his time and effort! The meeting was called to a close at about 8:00 pm. Our thanks to all who attended!
Joe Butler of Chomerics points out current standards committee work on shielding effectiveness standards to the Phoenix Chapter. Photo by Steve Gerard.
Download Joe Butler's presentation by clicking here.
Harry Gaul reports that 18 people attended the May meeting of the Phoenix EMC Chapter. Dave Staggs gave a brief presentation on the upcoming EMC Symposium and 50th anniversary celebration of the EMC Society to be held in Hawaii this summer. Dan Hoolihan was the featured speaker with a topic entitled “Understanding the Latest Changes to IEC 17025 for EMC Lab Accreditation.” Dan began his talk by offering suggestions on how to select an EMC Lab. First, you should make sure the lab is accredited to ISO17025:2005 and then verify that the scope of accreditation covers all of your tests. The ISO17025 document covers all kinds of labs, not just EMC. The document includes both management requirements as well as technical requirements. One of the highlights of ISO17025 is that a lab needs to seek feedback from its customers, both positive and negative. Also corrective action using root cause analysis should be undertaken to correct error prone processes. In particular, Dan mentioned that a lab’s measurements should always fall within plus or minus two standard deviations. This should be checked on a routine basis by performing intermediate checks such as measuring the E-field level of an FM radio station.
Dan Hoolihan presents Tom Karas of Motorola and Jim Vogler of National Technical Systems with IEEE beach towels to commemorate the 2007 EMC Symposium in Hawaii. Tom and Jim won the towels as door prizes at the May meeting of the Phoenix Chapter. Photo by Steve Gerard.
The third IEEE EMC Phoenix Chapter meeting of the 2006-2007 season was held on February 21, 2007 at Garcia’s Mexican Restaurant, in the Embassy Suites Hotel at Rural Road and I-60 in Tempe, AZ.
The meeting began with the customary social hour starting at 5:30 pm, with dinner at six. Again, we had a excellent attendance, with even more new faces than December's meeting!
After we all had our fill of Garcia’s Mexican food chapter chairman Harry Gaul called the meeting to order at 7:15 pm. Business began with the introduction of our new chapter officer, as Jim Dykema has joined us as treasurer. Welcome Jim! We then continued with our customary round table introductions and the call for EMC employment/employers. We are also searching for any interesting speakers for our next chapter meeting. If you have any ideas for speakers, please contact one of the chapter officers.
After the general chapter business was completed, Harry introduced our featured speaker, Michael J. Oliver of MAJR Products Corporation.
Mr. Oliver is Vice President of Electrical / EMC Engineering at MAJR Products Corporation responsible for customer technical quoting and consulting, new product development, and is the ISO-9001:2000 management representative. His expertise is in EMI/RFI shielding technology with a background in electronics, military shelter electrical systems, and high power antenna / radome design. He holds a B.S. degree in Electrical Engineering from Gannon University and has been an Electrical Engineer since 1989. He currently holds three patents (two pending), on EMC shielding - thermal management devices. He currently serves as Chairman of the newly formed IEEE Pittsburgh EMC Society, Vice Chairman of the SAE AE4 Electromagnetic Compatibility Committee, and member of the IEEE EMC Standards Advisory Coordination Committee (SACCom).
Mr. Oliver started the presentation by reviewing EMC fundamentals, including basic definitions of EMC terminology. He mentioned a very interesting Georgia State University web site at http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html, which has an excellent glossary of electromagnetic and other Physical terms. He pointed out the distinctions between Differential Mode versus Common Mode noise interference generation, and potential mitigation methods for each (including shielding). He mentioned that common mode interference is generally more predominant. He also discussed Plane Wave versus E-Field and H-Field shielding, and provided equations for each. A good rule of thumb dictates that material type dominates shielding effectiveness below 10 MHz and holes or apertures dominate shielding above 10 MHz. He also mentioned how partial shields may not operate as intended since they can actually increase emissions on the 'unshielded' side.
Mr. Oliver then discussed the MIL-DTL-83528 shielding test method, and recommends that non-conductive bolts or fasteners should be used when making this measurement. He also mentioned that Beryllium-Copper makes an excellent shielding material, but care should be used in instances where RoHS compliance is mandatory. According to Mr. Oliver, 2% beryllium is generally considered acceptable.
Mr. Oliver then explained concepts of aperture shielding. For slot apertures, shielding can be estimated by the equation SE = 20 log (Lambda/2L), where L is the longest dimension of the slot. Hole aperture shielding can generally be estimated by SE = 40 log (Lambda/2L). If multiple apertures are present, shielding loss is proportional to 20 log N, where N is the number of apertures within Lambda/2. MAJR Products Corporation has an excellent Excel-based design tool to assist with shielding calculations at their website: http://www.majr.com/.
Regarding Honeycomb vent panels, a 4:1 thickness to width ratio is considered ideal. Remember that nickel or tin plating is important to reduce the effect of 'Glue Lines' in the honeycomb material. Mr. Oliver recommended MIL-STD-1250 as a good resource for galvanic corrosion.
After the presentation, Harry Gaul presented Mr. Oliver with a beautiful Arizona Highways Calendar for his excellent presentation. We would very much like to thank Mr. Oliver for his time and effort!
The meeting was called to a close at about 8:30 pm. Stay tuned for upcoming speakers. Our thanks to all who attended!
Harry Gaul presents Mike Oliver with an Arizona Highways calendar on behalf of the Phoenix Chapter. Photo by Steve Gerard.
Click HERE to download Michael Oliver's presentation on Shielding Theory and Design.
The second IEEE EMC Phoenix Chapter meeting of the 2006-2007 season was held on December 6th 2006 at Garcia’s Mexican Restaurant, in the Embassy Suites Hotel at Rural Road and I-60 in Tempe, AZ.
The meeting began with the customary social hour starting at 5:30 pm, with dinner at six. We had a good attendance, with many new faces! We were also pleasantly surprised by the attendance of a long-time IEEE-EMC and SAE member that we have not seen in a while – Dwayne Awerkamp.
After we all had our fill of Garcia’s Mexican food, Harry Gaul, our chapter chairman, called the meeting to order at 7:00 pm.
Business began with the customary round table introductions and the call for EMC employment/employers. We welcomed Hoosamuddin Bandukwala from Flom Test Labs, who mentioned that they may be looking for EMI Engineers and Technicians in the near future.
Harry Gaul also mentioned that it has been quite a while since we have had officer elections in our chapter, so he opened the floor to nominations for Chapter Chairman, Vice Chair, Secretary and Treasurer. Because of the overwhelming number of volunteers and nominees, Harry, Glen and Daryl continue to be the chapter officers!
After the general chapter business was completed, Harry introduced our featured speaker, Mr. Gary Fenical of Laird Technologies.
Mr Fenical is an EMC Technical Sales Representative at Laird Technologies in Delaware Water Gap, PA and has been with the firm for 23 years. Mr. Fenical has authored many articles on EMC Requirements for Medical Devices, Mutual Recognition Agreements and Guidelines to meet the essential requirements of the EMC Directive. He has also authored several seminars on the EU EMC Directive, International Compliance and Designing for EMC and EMC Requirements for Medical Devices, which have been presented worldwide.
At the end of 2004, the European Council and the European Parliament have formally adopted a revised Directive on Electromagnetic Compatibility (EMC Directive): the new Directive 2004/108/EC of the European Parliament and of the Council, of 15 December 2004, on the approximation of the Laws of Member States relating to electromagnetic compatibility, published in the OJEU on 31 December 2004 (L 390/24). This new Directive will replace the old Directive 89/336/EEC within three years (from 20 July 2007). The mandatory application of the new directive is 20 July 2009.
Mr. Fenical's presentation was a summary of a series of presentations that he attended in Brussels in February 2005. He was one of only a handful of US attendees, and therefore provides us with valuable insight into the impact of the new directive.
The new approach directive stresses meeting the essential requirements through the use of harmonized standards. The use of Technical Construction Files is removed. A manufacturer may choose to use harmonized standards (generally preferred) or may choose to use a technical file approach.
The new directive was a result of the 1998 SLIM report, which was the output of a panel of experts who advised the member states to clarify the original directive's scope and definitions, and to better define the essential requirements.
Mr. Fenical went on to describe the directive's definitions of Apparatus, Component, Passive Equipment and Mobile and Fixed Installations. One of the most important regulatory changes is how Fixed Installations are handled. No longer do all of the individual apparatus contained in fixed installations need to comply with the directive, as long as the fixed installation itself meets the essential requirements. Often this can be accomplished through the use of a technical file, which must be kept with the person responsible for the fixed installation and at the disposal of the national authorities. As the apparatus are imported, they must be clearly marked that they are part of the fixed installation in order to clear customs.
Exceptions to the new directive include RTTE (telecon equipment), Aeronautical equipment, and Amateur radio equipment. It is also important to note that the Harmonized Standards have not changed as a result of the new directive and they must be applied within their scope. Full responsibility of compliance is placed on the manufacturer or importer (in fact, it always has been), but the new directive does not require mandatory competent/notified body involvement if harmonized standards are not used.
Mr. Fenical also spoke of configurations and operating conditions of test items, including the use of 'normal operating conditions' unless a single worst-case operating condition can be identified. Product marking, traceability to the responsible person, precautions of use and clear restrictions of residential versus industrial operating environment are required. Technical files must be kept with the manufacturer for at least 10 years and Declarations of Conformity must have the required information and must be available to the authorities.
Market surveillance in the EU is a multi-tiered approach, including reacting to interference complaints, authorities attendance at trade fairs, surveillance of notified bodies, and inspection of fixed installations. Several members of the EU are serious about EMC, and are not to be taken lightly.
Generally, the new directive provides legislative changes only, and will not immediately affect most manufacturers or importers into the EU member states. However, it is very important to understand the upcoming changes of the European EMC directive so we can all be prepared. Our thanks to Gary Fenical for a very informative lecture!
After the presentation, Harry Gaul presented Gary with a beautiful Arizona Highways Calendar for his efforts.
The meeting was called to a close at about 8:30 pm. Our thanks to all who attended!
Gary Fenical of Laird Technologies explains the details of Europe's new EMC Directive to the Phoenix Chapter... Photo by Steve Gerard.
The October IEEE EMC Phoenix Chapter meeting was held on October 29th at Garcia’s Mexican Restaurant, in the Embassy Suites Hotel at Rural Road and I-60 in Tempe, AZ. The meeting began with the customary social hour starting at 5:30 pm, with dinner at six. After we had our fill of Garcia’s great Mexican food, Harry Gaul, our chapter chairman, called the meeting to order at 7:00 pm. We had a good turn out with over a dozen EMC'ers attending.
Our featured speaker was Dr. Flavio G. Canavero, who received the Laurea degree in electronic engineering from the Politecnico di Torino, Torino, Italy, in 1977, and the PhD degree from the Georgia Institute of Technology, Atlanta, USA, in 1986. Currently he is a Professor of Circuit Theory and Electromagnetic Compatibility with the Department of Electronics, Politecnico di Torino. He is also presently the Editor-in-Chief of IEEE Transactions on Electromagnetic Compatibility, and will soon move on to become the editor of technical papers for the IEEE EMC newsletter!
Dr. Canavero started his presentation by explaining that Embedded/Integrated systems are becoming much more prevalent, and interact directly with the environment around them. Examples include ABS braking systems, entertainment systems, GPS receivers (in automobiles) just to name a few. These kind of embedded systems often have several integrated functions,, making EMC more important than ever. With time-to-market being a competitive driver, performing accurate simulations in the design phase without a prototype yet being available can be a competitive advantage.
Dr. Canavero discussed a three part simulation tool set that can be used to model three parts of a circuit, the integrated circuit, the interface bus/interconnects and connectors/discontinuities. The first part of the tool set is known as Mpilog, which stand for “Macromodeling via Parametric Identification of Logic Gates. Mpilog generates behavioral macromodels for the I/O ports of digital integrated circuits. Mpilog macromodels are mathematical relations approximating the port electrical behavior of devices, thus completely hiding the internal structure of devices and preserving the proprietary information of vendors. Mpilog allows the implementation of macromodels as SPICE-like subcircuits or as direct equation descriptions via metalanguages like VHDL-AMS. Furthermore, macromodels can be directly used in any EDA tool supporting the IBIS ver. 4.1 description of digital integrated circuits as externally defined models.
The second part of the tool set is know as IdEM, which stands for Identification of Electrical Macromodels. It is aimed at the generation of macromodels for linear lumped multiport structures (e.g., connectors, packages, vias, discontinuities, ...), known from their input-output port responses. The input-output characterization of the structure under investigation can come from measurement or simulation, either in frequency domain or in time domain. A SPICE link allows the automatic synthesis of the macromodels into equivalent circuits that can be processed by standard circuit solvers.
The third tool is knows as TOPLine, which is used to develop macromodels for busses and interconnects. Each of these tools generate output models that can be used as building blocks for simulations of large circuits or systems. Throughout the presentation, Dr. Canavero showed validations of the tools results. The final summary indicated that large circuits, which either took inordinate amounts of time to simulate, or could not be simulated at all using typically available computer hardware, were solved within reasonable time frames using the simulation tool set that Dr Canavero demonstrated. For further information, please see Dr. Canavero's website at: http://www.emc.polito.it/home.asp. After the presentation, Harry Gaul presented Dr. Canavero with a beautiful Arizona Highways Calendar for his efforts. Our chapter thanks Dr. Canavero for a very interesting lecture and our thanks to all who attended!
In his talk on Electromagnetic Compatibility of Integrated Systems, Dr. Flavio Canavero explains to the Phoenix Chapter the need to account for additional properties beyond the IBIS models. Photo by Harry Gaul.
Glen Gassaway reports that the featured speaker in March was Dr. Franz Schlagenhaufer of the Western Australian Telecommunications Research Institute (WATRI). The meeting began with the customary social hour starting at 6 pm. After we had our fill of Garcia’s great Mexican food, Harry Gaul, our chapter chairman, called the meeting to order at 7:00 pm. It was immediately apparent that we had another excellent turn out, with over 20 persons attending, including one from Tucson.
Dr. Schlagenhaufer told us that numerical field simulation is a useful tool for achieving electromagnetic compatibility on a system level. Numerical field simulation results may not have extreme accuracy on complex system models (as may be necessary for precise RF models), but generally EMC problems do not require that level of accuracy. During the simulation process, it is important to neglect as many unimportant details as possible to speed up the simulation, while keeping essential details. Therefore, performing meaningful simulations can be somewhat of an art form. System simulations are not meant to replace actual measurements, but are very useful in providing problem insight, supporting problem solving, and predicting the responses of design modifications.
Situations when numerical simulations should be performed include: a) when the product is not available (such as shipboard antenna structures), b) when controlled variations of parameters are not possible (such as lightning strikes on transmission lines) and c) when the physical value of interest is not easily obtainable (such as the inductance value of complex structures).
Dr. Schlagenhaufer’s presentation addressed the five basic steps of a typical simulation procedure: Modeling, Meshing, Computation, Result Validation, and Post-Processing Routines. Modeling includes transforming the physical model into a mathematical one. It is important to simplify and neglect non-essential parts of the physical model. It is important to know if the modeling assumptions are reasonable, and if adequate computer resources are available. Meshing includes converting the model into something the computer can understand. Segment sizes should be based on wavelength and structural discontinuities. Computation is generally done by the program itself. Presently available software is usually very accurate, but the output is only as good as the model. Before attempting the computation process, it is important to estimate calculation time and computer resource requirements. Result validation is often done by reviewing boundary conditions, power budget, field and current distributions and the model’s sensitivity of the variation of input data. Post-processing is required to display the results in a meaningful manner. Perhaps the best data display could be a set of observation points versus frequency, an observation line, or an observation plane. Combinations of these or other displays may also be meaningful.
Dr. Schlagenhaufer closed the presentation with the
following remarks: When it comes to field simulation for complex systems,
some particularities can be noted. The outcome from the simulations will,
in most cases, not be the final result, but rather the simulation results
will be the input data for further systems analysis.
After the presentation, Harry Gaul presented Dr. Schlagenhaufer with a
beautiful Arizona Highways Calendar for his efforts. Our chapter thanks
Dr. Schlagenhaufer for a very interesting lecture!
In his talk on electromagnetic modeling, Dr. Franz Schlagenhaufer explains to the Phoenix Chapter the need to increase the mesh density near edges where the current is rapidly changing. Photo by Steve Gerard.
The IEEE EMC Phoenix Chapter was proud to host the January 2006 RF-EMC-Wireless Tech Tour at the Embassy Suites Hotel in Tempe, Arizona. The RF-EMC-Wireless Tech Tour is an on-going series of technical learning sessions that will travel to Melbourne, FL, the Metro D.C. area and to Boston, MA later this year. Registration began promptly at 12:30 and it was soon apparent that this was to be a well-attended event. Once everyone was seated, the first presentation started on time at 1pm.
The first paper was presented by the IEEE Phoenix Chapter’s own chairman Harry Gaul, who presented a paper on “The Influence of Ground Plane Reflection on Antenna Calibration and Measurements”. This presentation started out with a riddle: Which configuration is likely to have a better chance of reception given a 2 km distance between antennas at 450 MHz with a height of 2 meters (assuming a direct line of sight): across a still lake; across a golf course with mounds; or would both scenarios be equal?
Harry’s presentation provided the theory and details of performing antenna calibrations in both free space and ground plane configurations in accordance with standards such as ANSI C63.5 and SAE ARP958. The concept of Normalized Site Attenuation (NSA) was introduced as a means to derive the difference between free space and ground plane test configurations. Antenna range measurements were also discussed from the standpoint of how to include the effects of reflection from earth with finite conductivity. It was concluded that ground plane reflections can induce serious errors if not properly accounted for during antenna calibrations and measurements. The effects of specular ground plane reflections can easily be modeled with today’s sophisticated mathematical software and additional considerations should include mutual coupling and the effects of cables.
By the way, the answer to the riddle is that the golf course is more likely to provide good reception because of the deep nulls that are possible from the lake.
The second paper, entitled “Anechoic Chamber Solutions for Antenna Pattern Measurements (APM)”, was presented by Dr. Vince Rodriguez of ETS-Lindgren.
This presentation introduced the user to antenna ranges, and concentrated on rectangular and tapered anechoic chambers for APM. Rectangular chambers tend to have less critical source placement, and are the ideal configuration for swept frequency measurements. Tapered chambers tend to be better for lower frequencies, but have potentially higher bore sight errors. Absorber technology, quiet zone levels, and far field requirements were discussed as well as the proper absorber treatment for both tapered and rectangular chambers. Large compact range chambers were also discussed.
The final paper, entitled “Improving the Accuracy of EMI Emissions Testing”, was presented by James Young of Rohde & Schwarz. This presentation discussed the advantages and disadvantages using a spectrum analyzer versus an EMI Receiver to make EMI measurements. Spectrum analyzers must be used carefully due to the possibility of reduced frequency accuracy over large frequency ranges. For example, a span of 970 MHz (30 MHz to 1 GHz) results in approximately 1 MHz frequency resolution if the spectrum analyzer has 1001 bins across its display. Given a 120 kHz CISPR bandwidth over this range, the bin size is larger than the bandwidth, and frequency resolution is lost. Additional concerns regarding EMI measurements with spectrum analyzers include less control of dwell time, potential 3 dB versus 6 dB resolution bandwidths, and less dynamic range and overload protection.
However, the spectrum analyzer is a very versatile instrument, and may be used for EMI measurements as long as its limitations are well understood. The presentation suggested that a spectrum analyzer or test receiver may be used for initial scanning to make a frequency “hit-list” as well as for maximization, and that the test receiver is optimal for making final measurements. The presentation went on to review the issues of RF and IF overdrive as well as the problems and benefits of using low noise amplifiers for increased sensitivity.
Once the presentations were complete a reception was held with the speakers, including hands on demonstrations and a drawing for prizes. Congratulations to Dennis Kennedy for winning the IPOD and David Lee for winning the 1GB memory stick.
The IEEE Phoenix Chapter wishes to thank all of those who made the Tech Tour possible, including the sponsors: Rohde and Schwarz, ETS-Lindgren, TMS Marketing, and Conformity Magazine. We would like to thank all of those who participated in this very successful event!
James Young of Rohde & Schwarz speaks to over 60 people that attended the ½ day Tech Tour Workshop, which was hosted by the Phoenix Section. Photo by Steve Gerard.
Phoenix Chapter Chair, Harry Gaul, concludes his presentation with a discussion of other sources of errors that can occur when performing antenna measurements and calibrations. Photo by Steve Gerard.
Dr. Vince Rodriguez of ETS-Lindgren points out the differences in rectangular and tapered anechoic chambers for antenna pattern measurements to the Phoenix Chapter. Photo by Steve Gerard.
Glen Gassaway reports that the November 2005 IEEE EMC Phoenix Chapter meeting was held on November 9th at Garcia’s Mexican Restaurant, in the Embassy Suites Hotel at Rural Road and I-60 in Tempe. This was the second meeting of the 2005/2006 season.
The meeting began with the customary social hour starting at 6 pm. After we once again had our fill of Garcia’s wonderful food, Harry Gaul, our chapter chairman, called the meeting to order at 6:55 pm. Business began with roundtable introductions and the call for EMC employment/employers.
Harry then discussed potential upcoming chapter meetings and announced the upcoming “Tech Tour: Aerospace EMC” Half-Day Technical Seminar, which will be held on Wednesday, January 25, 2006 in the same Embassy Suites Hotel where the chapter normally meets (4400 South Rural Road in Tempe). Guest Speakers for the event will be James Young of Rohde & Schwarz, Vince Rodriguez of ETS-Lindgren and our very own Harry Gaul of General Dynamics C4 Systems.
After the general chapter business was completed, Harry introduced our featured speaker, Ray Adams. Ray is a Senior Project Manager with Fischer Custom Communications, Inc, and has been the Los Angeles IEEE EMC Society Chapter Chair since 1992.
The amount of money that is spent performing MIL-STD-461 EMC Tests warrants attention to detail so that a successful and efficient EMC Test is performed. This is particularly true with the qualification of any new system or system upgrade.
Ray discussed methods of successful EMC test planning, including gaining a full understanding of how the equipment under test (EUT) operates, the physical layout of the EUT, the selection of proper operational modes, and the EUT harnessing, grounding and power returns.
Ray mentioned that it is imperative to write a useful EMI test procedure which includes a full comprehension of the intent of every test. A well written procedure should not rely heavily on a ‘boilerplate’ test procedure. During a test, it is critical to carefully follow the procedure, document deviations, and to maintain an EMC test logbook. The EUT susceptibility criteria should be carefully defined and non-value added testing should be avoided, since it can increase test time and cost. Ray presented several sample susceptibility criteria for a number of different EUT.
Ray also discussed several methods to improve EMC test setups, including understanding the limitations of the test equipment. He went into detail discussing the effects of preamplifier and spectrum analyzer overload and how it can be mitigated.
Ray then reviewed the pitfalls of poor design of EUT monitoring equipment. It is important to prevent the monitoring equipment from becoming the dominant noise source or from inducing EUT susceptibility. Ray indicated how one could analyze susceptibility test signal coupling paths and estimate required RF isolation. Troubleshooting methods should focus on careful review of test data and only one variable should be changed at a time. Test reports should include a test equipment list, a summary of test performed with results, test set up photographs, test data, transducer factors and a copy of the redlined test procedure.
Ray summarized the presentation by declaring that successful EMC tests are possible, but careful preparation is necessary and thorough EMC test procedures are required. For more information, Ray can be contacted at: radams@fischercc.com.
Harry Gaul then presented Ray with a beautiful Arizona Highways Calendar for his efforts. Our chapter thanks Ray for a very informative presentation!
The meeting was called to a close at about 8:00 pm. Thanks to all who attended!
Ray Adams points out potential RF leakage points when conducting RS103 testing to the Phoenix Chapter. Photo by Steve Gerard.
Glenn Gassaway reports that the October 2005 IEEE EMC Phoenix Chapter meeting was held on October 12th at Garcia’s Mexican Restaurant at Rural Road and I-60 in Tempe. This was the first meeting of the fall season, and was very well attended!
The meeting began with the customary social hour and dinner from 5 to 7pm. After we all had our fill of Garcia’s wonderful Mexican food, Harry Gaul, our chapter chairman, called the meeting to order at 7:00. Business began with roundtable introductions and the call for EMC employment/employers.
Harry mentioned that General Dynamics in Scottsdale is looking for engineers experienced in ionizing radiation effects and Joe Chott mentioned that General Dynamics in Gilbert may soon be looking for experienced EMI design engineers (pending internal search).
Harry also discussed potential upcoming speakers. It became apparent that this year will bring a variety of interesting speakers to our chapter! We are also looking forward to a special event in January (more to come).
After the general chapter business was completed, Harry introduced our featured speaker, Jim Reed. Jim has worked in 3D EM simulation since 1997 starting with antenna design at TRW Space Park. After TRW, Jim worked with Ansoft in 1998 to support their frequency domain product HFSS. Upon moving back to his home state of Texas in 1999, he developed his own company for 3D EM simulation services, which led to his introduction of CST’s time domain product Microwave Studio. He worked for CST for over 3 years in support, sales and marketing. In May of 2003, Jim returned to promoting his own engineering services for 3D EM simulation with his company Optimal Designs.
Jim’s discussion focused on the two initial solution domains used to calculate the electrical properties of a device - frequency domain and time domain. Each domain has advantages and disadvantages which affect the solve time.
Jim presented a brief introduction of frequency and time domain calculations with an emphasis on the meshing technique. Several EMC examples were presented using both Ansoft HFSS frequency domain and CST Microwave Studio time domain with consideration to model setup for accuracy and solve time.
Jim went through the five basic indicators of when time or frequency domain simulation should be used. Electrically large models often solve faster in time domain. Models with high mesh aspect ratio are generally more suited for frequency domain simulations with tetrahedral mesh. Large bandwidth models should focus on time domain simulations, since a single simulation excites a broad range of frequencies in the time domain. High Q devices should typically use frequency domain simulations, since time domain solutions of these devices may be lengthy due to their energy storage and long decay times. Finally, frequency domain simulations should be used for models with a large number of ports.
Jim then presented several examples. The first example used CST’s Microwave Studio (time domain) to solve for the radar cross section of a 10 inch ‘almond’. The second example showed how Ansoft’s HFSS (frequency domain) solved for a small gap. The third example showed how Microwave Studio simulated a blade antenna. This example showed how to establish entry ports and boundary conditions. The fourth example showed how Microwave Studio simulated a cavity resonator (a device with a long decay time). Even with simple geometry, the simulation of this high Q device in the time domain was rather lengthy. The last simulation showed how HFSS simulated a microstrip connector with a complex form factor.
The conclusion of the presentation conveyed that both domains are accurate for all passive 3D devices if used properly, but there are clear advantages in solve time and improved accuracy if the proper solution domain is chosen.
Jim mentioned that the proper utilization of modeling software was extremely complex and could only be lightly covered in the allotted time given in our chapter meeting. Through his company, Jim provides much more detailed presentations on this subject matter. Jim can be contacted at jim.reed@optimal-designs.com.
The chapter thanks Jim for a very interesting presentation indeed.
Harry Gaul then called the meeting to a close at about 8:00 pm. Stay tuned to your email for the next meeting announcement, which should be in about a month. Thanks to all who attended!
Jim Reed discusses the 5 indicators of when to use frequency domain and when to use time domain EM solvers to the Phoenix Chapter. Photo by Steve Gerard.
The May 2005 IEEE EMC Phoenix Chapter meeting was held at Garcia's Mexican Restaurant at Rural Road and I-60 in Tempe. This time, the meeting was held on a Wednesday (May 25) as opposed to our usual Thursday night. Our next meeting will be in the fall because our chapter tends to take the long, hot Arizona summers off to enjoy family vacations and escape the heat! After chapter business, Harry Gaul introduced our featured speaker, Prof. Dr. - Ing. Heyno Garbe, a Distinguished Lecturer of the EMC Society. Professor Garbe is currently Dean for Education at the Department of Electrical Engineering and Information Technology at the University of Hannover, Germany. Professor Garbe is very active in several EMC related national and international standardization committees. He is a Senior Member of the IEEE, as well as a member of URSI Com. E, VDE, and the IEEE EMC, AP, IMT and MTT Societies. Since 1997, he has served as chairman of the German chapter of the EMC Society and is currently serving on the Board of Directors of the EMC Society.
Professor Garbe started his presentation "Understanding and Avoiding EMC Problems of LANs" by covering the basic fundamentals of attenuation and Near End Cross Talk (NEXT). He spoke of field coupling to several kinds of wire structures, and the effects of common mode to differential mode transformation in balanced versus unbalanced transmission lines. He defined LAN cable structures and their uses including internal shields which tend to reduce wire-to-wire crosstalk, and overbraid shields which reduce field to cable coupling. He also covered digital noise sources that one may encounter in a LAN system. For instance, LAN-emitted digital noise tends to be stochastic and it is important to calculate the power spectral density to ascertain if a noise problem may be evident. Interestingly, Professor Garbe showed a graph which compared the power spectral densities of 10, 100 and 100 base-T Ethernet signals, which showed that 10 base-T signals have the highest amplitude in the lower frequency ranges. If a system tends to be susceptible in the 10 base-T range, then the 10 base-T emitter would be worst-case among the three. The important thing to understand is that the digital encoding affects the potential of susceptibility.
Professor Garbe also mentioned the importance of a well terminated cable shield. Terminating a cable shield at one end is not enough. Dr. Garbe showed experimental results indicating that a one-end terminated shield would have the same shielding effectiveness as a completely unshielded cable at higher frequencies where LAN noise is prevalent. He joked that one could save money by simply avoiding all shielding if the design included one-end termination. He also spoke of long pigtail terminations, which are responsible for poor shielding effectiveness. One conclusion that that he drew was that the radiated emissions from LAN cables due to the differential signal is pretty small because of the balanced nature of the signal. The more severe threat is power supply chopper noise which may be present on the LAN wiring. In this case, the power supply noise is common mode so the twisting/balancing provides no reduction. Thus, the shielding of the twisted pairs is necessary to reduce the emissions.
Professor Garbe covered the increasingly popular Broadband Power Line Communications Systems, which of course are not shielded. He implied that these are noisy systems indeed. Several questions arose at the end of the talk, including a lively and positive exchange discussing the importance of maintaining a 'balanced' design.
Stay tuned to your email for the next meeting announcement, which will be after summer Thanks to all who attended!
Click HERE to download Dr. Heyno Garbe's talk on Understanding the EMC Problems of LANs.
Professor Garbe addressed the Phoenix Chapter with a talk entitled "Understanding and Avoiding EMC Problems of LANs". Photo by Steve Gerard.
Harry Gaul reports that at the April meeting of the Phoenix EMC Chapter, our very own Daryl Gerke gave a well-received talk on "Diagnosing and Troubleshooting EMI Problems". Daryl began the talk by sharing his philosophy of troubleshooting that he's refined over many years of being an EMI guru troubleshooter. First, one has to develop an "emergency room" mentality with a fast response because the "patient" is often in pain. The initial information is often confusing or incomplete. And the situation may be tense so one has to keep cool. One must first diagnose and then try fixes because "prescription without diagnosis is malpractice". Daryl offered up many examples of failures and fixes ranging from ESD to emissions to power disturbances. He also addressed the pros and cons of fixes implemented at the board level versus at the enclosure level. Daryl shared the contents of his magic box of tricks including foil, copper tape, screen, ferrites, and EMI filters. Daryl concluded his talk by emphasizing the need to first diagnose the problem through the gathering and critiquing of data followed by making a plan. The actual fixing of the problem then involves iterating between predicting and monitoring the outcome of fixes.
Daryl Gerke explains the critical factors affecting radiated emissions to the Phoenix Chapter in his talk on Diagnosing and Troubleshooting EMI Problems. Photo by Steve Gerard.
Harry Gaul reports that the November 20th meeting included a talk given by David Lee, the Compliance Test Manager for M. Flom Associates in Chandler, AZ. In this talk entitled, Demystifying the Process for Certifying Low Power Transmitters, David Lee focused on the rules and processes for certifying low power transmitters for the FCC, Industry Canada, and the CE Mark (ETSI) requirements.
Dave pointed out that the 47CFR Part 2 contains all of the "gotchas", ie., the rules and core tests which are then modified by the other parts such as Part 15. He also pointed out that Specific Absorption Rate (SAR) testing often requires performing the tests across all the accessories such as antennas and batteries, and can therefore become quite expensive.
Dave stated that the 47CFR rules are quite intertwined, especially 15.247 for frequency hopping and direct sequence spread spectrum radios. The RS210 document for Industry Canada is roughly equivalent to the FCC Part 15 and Part 18. He also said humorously that the EU is a collection of feudal warring states especially when it comes to the harmonization of frequency bands. Finally, Mr. Lee projected that the FCC rules may incorporate immunity tests in the not-too-distant future.
Harry Gaul presents a bottle of Arizona salsa to Mr. David Lee of M. Flom Associates who presented a talk at the November 2004 Phoenix Chapter meeting. Photo by Jim Dykema.
Glen Gassaway reports that once again there was standing room only at the IEEE EMC Phoenix Chapter's meeting at Garcia's Mexican Restaurant on Rural Road and I-60 in Tempe. The meeting was held on Thursday, September 30th, and was the kickoff to our new season (since we tend to take the hot Arizona summers off). The meeting began with the customary social hour from 6 to 7pm, which gave all of us time to socialize with friends and past-coworkers that we may have not had time to contact since last spring. After we all had our fill of Garcia's wonderful food, Harry Gaul, our chapter chairman, called the meeting to order at 7:00. Business began with the call for EMC employment/employers, which went unanswered. It looks like everyone is gainfully employed. Then Harry introduced our infamous Vice chair, Daryl Gerke, who told us of potential future speakers that we may be able to convince to present at our gatherings. Finally, Daryl, introduced our guest speaker, Bill Parker.
Bill Parker began work as an EMC engineer at Genisco Technology Corporation in 1973. After various assignments at Genisco, he started his current EMC consulting business in 1989 and is still going strong. Bill teaches EMC seminars and provides consulting, testing, and teaching services, as well as being very active in the IEEE EMC Society. It was also interesting to hear that Bill is an avid runner, and has even participated in the LA marathon!
Bill's presentation, entitled "Down Memory Lane; 30 Years of EMI Field Testing" revolved around his vast EMI field testing experiences. He related several "war-stories" including stories of testing in terrible conditions for long hours, on-site tests of engine-generators, motor-generators, uninterruptible power systems, as well as testing portions of larger equipment, such as a Navy submarine, and even the Space Shuttle Challenger! He took us 'down memory lane' by showing us photos of older EMI test equipment, bringing back the good old days for us old-timers. He told us of his exploits in his test equipment van and how to be fully-equipped for an upcoming field test. Bill had too many stories to list in this article, which could never do them justice - you just have to hear them for yourself!
Bill concluded his presentation with a discussion of significant lessons learned throughout the years, for example: using a flashlight, headphones, and a cheap AM/FM radio on a stick as a diagnostic tool for evaluating chamber shielding effectiveness.
Harry then called the meeting to a close at about 9:00 pm. Stay tuned to your email for the next meeting announcement. Thanks to all who attended!
After Bill Parker's presentation, Harry Gaul awards him the traditional
jar of Arizona salsa as a hearty thank-you for his entertaining
presentation! Photo by Steve Gerard
Glen Gassaway reports that Garcia's Mexican Restaurant had another
packed house at our April 22nd IEEE EMC Society Phoenix Chapter meeting.
After a lively social hour (where the drinks were on TMS's tab - thanks
Brent!), Harry Gaul was finally able to calm everyone down and get to
business. Harry reviewed a schedule of upcoming meetings, including
inviting Bill Parker in the fall for a thorough review of EMC 'war
stories'. Daryl Gerke may also be an upcoming presenter (stay tuned).
Finally, the chapter intends to host a ½ day colloquium on antennas in
January. There's more to come, too! Possibly in light of a
strengthening economy, the standard call for EMC employment went
unanswered - does that mean everyone is gainfully employed??.
Harry then introduced our featured presenter, David Seabury, a Senior
Business Development Manager with ETS-Lindgren. David began his
presentation, entitled: "A Review of Radio Frequency Exposure
Requirements of FCC OET65 and the Latest Direction of the IEEE/IEC
Standards". David explained that there are two predominant RF
exposure mechanisms that have enforceable standards in the US, including
"Maximum Permissible Exposure" (MPE) and "Specific
Absorption Rate" (SAR). The FCC's Office of Engineering
and Technology (OET) Guidelines described in OET-65 Ed 97-01 addresses
both mechanisms. MPE typically refers to the operation of RF-emitting
devices in the far field (>20cm distances) whereas SAR applies to
devices within 20cm of the body. MPE also allows either measured or
predicted assessments, whereas SAR almost always requires measured
assessments. Control methodologies for MPE involve a variety of
options, including limiting output power, time averaging, shielding,
antenna pattern management, or (the most popular) implementing personnel
access restrictions, including adding signs or fences. Enforcement of MPE
standards is increasing, with more actions and on-site reviews taking
place. In addition to the FCC, OSHA also enforces MPE limits, focusing on
the workplace. OSHA has by and large adopted the OET-65 limits, but also
addresses induced currents and covers a lower frequency range. Key
websites include:
www.fcc.gov/oet/rfsafety
www.osha.gov/SLTC/radiofrequencyradiation
In the United States, SAR regulations are covered by FCC OET supplement
C 01-01. It indicates the applicability of the 20cm rule - where the
fixed, mobile or portable device has to be operated within 20cm of a human
for the rules to apply. Europe's near equivalent standard is EN50630/50631
and most countries use the self-certification method of compliance.
Test methodologies for SAR include setting the device under test at the
highest RF power and probing localized temperature rises in a 'liquid'
phantom (head) or box (body). A signal generator and coupler are typically
used for pretest calibration checks and the tests are normally done in an
automated fashion, using a robotic arm for probe positioning. The
talk concluded with an update of the work being performed in the standards
committees and the potential impact to the FCC's requirements.
After David Seabury's presentation, Harry Gaul awarded him the customary jar of salsa. Thanks to David for your informative presentation! Photo by Steve Gerard.
Harry Gaul reports that we had an exciting time at the February 19th IEEE EMC Society Phoenix Chapter meeting held at the Marriott Mountain Shadows in Scottsdale. This was a joint meeting held in conjunction with the EMC Society's Board of Directors' meeting. The attendees enjoyed some wonderful hors d'oeuvres and drinks by the pool prior to the presentation on reverberation chambers by Mike Hatfield of the Naval Surface Warfare Center Dahlgren Division.
Mike spoke on "How To Conduct Electromagnetic Effects Testing Using a Microwave Oven and a Pair of Dice, Or, A Statistical Approach For Conducting System Electromagnetic Vulnerability Assessments." Mike began his talk with a short history of actual devastating HERO problems in the Navy followed by an in-depth look at the statistical basis for repeatability in mode-tuned chambers as a function of the number of tuner positions. The premise of Mike's talk was that large uncertainties in the test process would lead to inconclusive statistical results for the safety of ordnance systems. He contrasted the typical anechoic chamber test method which tends to have too few of aspect angles versus mode-stirred chambers where the directivity tends to get washed out. Mike made the comment that the peak of the mode-stirred responses will equate to the average of the anechoic chamber responses given a sufficient number of tuner positions in the reverberation chamber and aspect angles in an anechoic chamber. Mike provided some interesting test results for measuring the shielding effectiveness of boxes. As it turned out, the anechoic chamber results were much more uniform when a mechanical stirrer was placed inside the box. The test results obtained in reverberation chambers were amazingly repeatable across multiple test labs. A lively discussion ensued at the end of the presentation concerning stirring as opposed to stepping the tuner and the loss of statistical significance because of the response time of the unit under test.
Mike Hatfield of the Naval Surface Warfare Center Dahlgren Division explains the importance of performing electromagnetic testing with predictable uncertainties. Photo by Steve Gerard.
The Phoenix EMC Chapter and their spouses attended the Phoenix IEEE Section's Annual Awards Banquet where vice-chairperson, Daryl Gerke, won a technical achievement award for his presentation on the "Mysteries of Grounding". From left are Harry and Lo-An Gaul, Steve Gerard, Terry and Suzie Donohoe, and Mary and Daryl Gerke. Photo by Steve Gerard.
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