Category Archives: Seminars

Update on Activities

Hi All,

Free EMC Guides – This last year, Interference Technology (IT) has posted several free downloadable guides to EMC. Some of the more recent ones include EMC Fundamentals, EMC Test, Medical EMC, and Military & Aerospace EMC. We’ll have a new 2017 Automotive EMC Guide coming out this week, as well. Please review all these at the bottom of our web page: http://www.interferencetechnology.com.

Looking for Authors – We’re looking for authors! IT has a long history in publishing the very best technical articles and reference material in the field of electromagnetic compatibility. It was first published starting in 1971 and I actually started subscribing to it in the mid-1970s – well before I knew I would end up in a career as an EMC engineer and consultant. Now I find myself as editor of that same publication – a humbling responsibility. You’ll find our Author’s Guide under the link, “Contribute”, at the bottom of the home page.

May Seminars – In other news, May was a busy month for seminars, with presentations in Chicago, Detroit and Israel. I was honored to be the featured speaker for the IEEE EMC Society in both Chicago and Detroit, and then was off to Israel to present a tutorial on Radiated Emissions Troubleshooting at DGCON (similar to DesignCON).

Upcoming Seminar – I’ll also be scheduling my regular two-day intensive EMC design, theory, troubleshooting, and pre-compliance testing seminar in Longmont, Colorado this coming September 19-20, 2017. This time, I’ll have guest speaker, Eric Bogatin, who will present a segment on “Power Distribution Network (PDN) Design for Low EMI”, based on his recent book on the topic. Should be a great program! Info and registration here: https://www.nts.com/resourcecenter/events/seminars/emc-essentials#

Webinars – Finally, for all of you who live outside the U.S., or who are unable to travel to one of my EMC seminars, this is for you! Washington Labs is hosting webinar presentations by myself, Robert Hanson, and Steven Ferguson on EMC Design & Troubleshooting. More info and registration here: http://wll.com/academy/2017-Webinar-Series-EMC-Design-Troubleshooting.html

That’s all for now, stay tuned for more!

Update on my activities

Hi All,

Sorry there’s been such a lapse since the last time I posted. Having accepted the position of senior technical editor for Interference Technology (IT) last December has kept me drinking from a firehose, as they say. Since the first of the year, IT has published my Real Time Spectrum Analyzer Guide, a free download on the web site: http://www.interferencetechnology.com. We also released the first of two print reference issues this year, the 2016 Directory and Design Guide.

IT has a long history in publishing the very best technical articles and reference material in the field of electromagnetic compatibility. It was first published starting in 1971 and I actually started subscribing to it in the mid-1970s – well before I knew I would end up in a career as an EMC engineer and consultant. Now I find myself as editor of that same publication – a humbling responsibility. Please register at the web site to start receiving our newsletters and notification of future guides on various fields of EMC. We’ll be releasing guides to Military EMC, EMC Shielding, EMC Filters, and Automotive EMC throughout the rest of this year.

In other news, I’ve had to halt my blogging for EDN.com, as the columnist for “The EMC Blog”, since taking the reins of IT. Fortunately, my good friend and colleague, Arturo Mediano, a professor and consultant from Spain, has agreed to start up the blog again in my place. He’s a brilliant EMC engineer and instructor and will bring a whole new take on practical EMC design and troubleshooting. Check it out at http://www.edn.com, then click on Communities > Blogs, then scroll down until you find “The EMC Blog”.

I’m scheduled to help teach a one week course during the next “EMC Week in Boulder City”. My topic will be EMI Troubleshooting and Pre-Compliance Testing. Check out the details and register here: http://www.dsmith.org.

I’ll also be scheduling my regular two-day intensive EMC design, theory, troubleshooting, and pre-compliance testing seminar in Longmont, Colorado this fall. Stay tuned for dates and pricing.

Finally, for all of you who live outside the U.S., or who are unable to travel to one of my EMC seminars, this is for you! I just completed the development of an intensive ON-LINE six-lesson course, EMI Troubleshooting and Pre-Compliance Testing”, which will be hosted by my friend Andy Eadie. The lessons are streamed as a video and may be viewed unlimited times. The cost is just $995 and full details and registration can be found at http://www.emcfastpass.com.

That’s all for now, stay tuned for more!

Your questions answered regarding cables and PC boards

Following the recent webinar sponsored by Rohde & Schwarz, I received way too many questions to answer during the live presentation, so I’m following up gradually and posting my answers on The EMC Blog, now hosted by EDN.com.

I’ve posted two articles so far:

1. Questions on cables for EMC mitigation

2. Questions on PC boards for EMC mitigation

I’ll be posting more soon on general EMC topics and pre-compliance testing for radiated emissions.

Presentation during the IEEE EMC Symposium

I’ve been invited to be the keynote speaker at the annual NEC EMIStream evening seminar and reception during the IEEE International Symposium on EMC, Thursday, August 8th, from 5:30 to 7:00 PM. The title of my presentation is “EMC Troubleshooting and Pre-Compliance Testing on a Budget”. For more details and to register for this free event, check out this link. http://www.nec.com/en/global/prod/emistream/ieee_seminar2013.html

Stitching Capacitors

Here’s a question from the last EMC webinar regarding “stitching capacitors” – what they are and how they’re used. While I attempted to answer the question during the Q&A session, things seemed a bit rushed, so here are some details.

A stitching capacitor provides a path for return current to flow back to it’s source. The capacitor would connect between the ground plane and power plane and must be located adjacent to where the signal trace changes reference planes. If the two planes are at the same potential, you only need to connect them together with a via at the place where the signal trace penetrates. Here’s a couple slides form my seminar that diagrams the issue. You can also run a ground trace (signal return trace through vias to do the same thing.

2-planes

Figure 1 – Here’s one of the most common issues from a slide taken from my EMC design seminar. If a clock trace needs to penetrate through two planes, how does the return current get back to the source?

If the two planes are the same potential – for example, signal return planes – then you can merely connect the two planes together with (typically two, or more) vias on either side of the clock trace. However, if the two planes are different – for example, signal return and power – then obviously, vias would not work, so we replace them with high-frequency bypass capacitors – i.e., “stitching” capacitors – on either side of the clock trace. Unfortunately, connecting each side of the capacitor to buried layers will require multiple vias, so to keep lead/trace inductance as small as possible, the vias must be located so as to minimize trace length and should be located as close as possible to the source clock trace penetration.

Stitching capacitors may also be used to provide a high-frequency connection across isolated planes, but this is a more advanced technique we can discuss at a later time.

Terminating shielded cables for low-cost unshielded products

Here is one of my “seed” questions I developed for the June 20th webinar in case not enough attendees asked questions. Fortunately, I didn’t have that problem, due to the tremendous response I received. In any case, while this wasn’t officially asked, the question does come up frequently.

Q: What if my product uses a plastic enclosure? Where do I connect the shield of the I/O cable?

A: Using shielded cables with unshielded enclosures can lead to design and performance issue for EMC. Many low cost consumer products can not afford a shielded enclosure, so how do we resolve this? The important thing to keep in mind is that there will inevitably be common-mode noise sources on the PC board. To keep these noise currents off our I/O and power cables, we can either block the currents from getting to the cables with a ferrite choke or divert the noise currents back to their source. Often, a combination of blocking and diversion is the best method. Many higher-end handheld consumer products use a diversion plate under the PC board. This method was described in another blog posting on The Connecting Edge and is merely a metallic plate or metalized film with one end bonded or clamped well to the I/O and power connector ground shells. This offers a low impedance path for the common-mode currents to flow back to the source through distributed capacitance. It also protects sensitive circuitry from external ESD currents injected at the I/O connectors. In addition, it serves as an image plane which helps reduce radiated emissions. To answer the question more directly, the cable shield must be bonded in some way to the digital ground (if a signal or I/O cable) and power ground (if a power cable). Ideally, all I/O connectors and power connectors should be grouped together on one side of the board. If they are spread all around the perimeter, that’s often bad news, as any noise sources on the PC board are now potentially driving the midpoint of a dipole antenna!

R&S Webinar, June 20, 2013

My first EMC webinar hosted by Rohde & Schwarz went off pretty well last Thursday, with 276 attendees from around the world checking in. Thanks to all for listening to some of the most common EMC issues I deal with during my consulting.

There were a number of questions asked, that I wasn’t able to get to due to lack of time, however, Rohde & Schwarz will be providing a list of the unanswered questions early next week and I intend to group like ones together and answer these periodically via this blog. Some of the more interesting questions will be answered on The EMC Blog, hosted by Test & Measurement World.

Thanks again for all who attended. I suspect we’ll do this again some time.