Some of my most popular articles

Hi All,

I thought you all might be interested in some of my most popular articles written for Interference Technology. Here are the top five:

The HF current probe: theory and application –

Inexpensive radiated immunity pre-compliance testing –

Spread spectrum clock generation – theory and debate –

Troubleshooting radiated emissions using low-cost bench-top methods –

Harmonic comb generators are useful tools –

Hope you enjoy them!

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: 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, 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, 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:

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

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

Really Small Drill Bit Set

For those of you who could use a set of really small drill bits, you might consider this set that ranges from 0.3 to 1.2mm in diameter. The cost is just $3.99 at Amazon. The company selling these is based in Asia, so the shipping time is about three weeks.



They come in a very nice plastic case and the bits themselves are cushioned.

They fit the 1/8-inch jaws of a standard Dremel tool.


The size markings are etched into the shank, so are difficult to read until just the right angle of light hits it – a magnifying loupe is a plus. They thinner bits break very easily, so it’s best to use a sturdy drill press for these, rather than a Dremel tool.

2014 Blog Highlights (Part 2)

Using current probes to estimate E-fields – Current probes are one of my most-used EMI troubleshooting tools. Frequently, a product’s I/O or power cables are often an appreciable fraction of a wavelength, so are a source of radiated emissions. This occurs if common-mode currents are allowed to travel along the cable or cable shield. Current probes may be used to measure these small (frequently in the uA) currents. Reducing such noise currents on those lines can often reduce the radiated emissions from the equipment under test.

Current probe Fig1-600

Gaps in return planes – yes or no? – As a participant during the panel discussion on EMC versus SI at the recent DesignCon 2014, I sensed (along with some in the audience) that there was disagreement as to whether it was OK to cross a gap in the return plane with a high speed, fast-edged, signal. Unfortunately, there was too little time in which to come to an agreement or to illustrate the conditions in which it was OK, or not OK. This article explains why this is NOT a good idea.

Gap in Plane-CM

Troubleshooting EMI on your bench top – If your product is failing radiated emissions at the test lab, it’s often more cost-effective to perform any detailed troubleshooting at your own facility where you can take time to methodically isolate the source and try out several potential fixes. Unfortunately, many companies don’t have the equipment or training to make these simple measurements. This article describes a easy method for measuring radiated emissions and providing a rough estimate of pass/fail.

Fig1-TS RE

Review: Signal Hound BB60C real time 6 GHz spectrum analyzer (Part 1) – The Signal Hound series of spectrum analyzers are about as small as three large-size Hershey chocolate bars stacked on top of each other. The unit offered for review is the recently released model BB60C real time analyzer, which can tune from 9 kHz to 6 GHz with a dynamic range of +10 to approximately -158 dBm (DANL, which is dependent on resolution BW). It can easily fit within a standard briefcase with room left over for a medium sized laptop.

Signal Hound BB60C 20140701-104

Review: Signal Hound BB60C real time 6 GHz spectrum analyzer (Part 2) – In Part 1 of this review, we discussed the basic architecture, specifications and controls of the Signal Hound BB60C real-time spectrum analyzer. In Part 2, we’ll show you some actual measurements and several screen captures.

STM32-F4 Controller 1 to 500MHz-600



2014 Blog Highlights (Part 1)

Sorry about getting a little behind in postings. Here are some of the highlights of postings on the site:

Review: inexpensive RF generator – During one of my presentations on low-cost EMC troubleshooting tools at the IEEE EMC Symposium last August, one of the attendees, Doug Miller, mentioned a small PC-controllable RF generator for just $190. Of course, I had to buy one and try it out!

Fig1-TPI Synthesizer-600

Review: Windfreak Technologies SynthNV RF generator – Every once in a while, I discover a product that is so incredible I wonder why it hasn’t been publicized more widely. This is the case with Windfreak Technologies $599 miniature RF generator, the model “SynthNV” (Figure 1). In case you’re wondering, their company is named after the owner’s sailboat!

WF Fig1

Detecting ESD Events – In my experience, electrostatic discharge (ESD) issues have now become the second-most prevalent issue other than radiated emissions. If you find your product has exhibits random upsets, such as loss of data or unusual circuit resets, it could very well be caused by ESD. This article describes several methods to detect these events.

ESD Detector

Harmonic Analyzer Tool – Because of their typically fast edge rates, crystal oscillators can generate a large number of high-order harmonics. This harmonic analyzer was created by my coauthor, Patrick André, with additional formatting tweaks by myself. I find this really handy to calculate harmonics from clock oscillators.

Review: TTi PSA2702T handheld spectrum analyzer – One thing that I find handy is a small hand held spectrum analyzer for use in troubleshooting EMI issues. As I travel a lot in my job, I like to take the minimum amount of test equipment possible. Unfortunately, most good quality analyzers are large, heavy and expensive. About ten years ago, I ran into the Thurlby Thandar Instruments (TTi) PSA2701T and have used it extensively since then. During that time, I reviewed it several times. In May 2013, TTi completely redesigned and repackaged this analyzer and released it as the PSA2702T. This is a review of the new PSA2702T, which I have used for several months now.


2013 in review

The prepared a 2013 annual report for my EMC blog.

Here’s an excerpt:

The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 11,000 times in 2013. If it were a concert at Sydney Opera House, it would take about 4 sold-out performances for that many people to see it.

Click here to see the complete report.

Measuring Resonance in Cables

Cables or other metal (antenna-like) structures often couple to sources of common-mode currents and end up radiating, causing product failures during compliance testing. During the troubleshooting process, it would be helpful to determine the resonance of these cables or structures to confirm they are the source of certain harmonic signals.

We could certainly measure the length of the cables or metal structures, but often, they are connected to other conductive assemblies, such as circuit boards or brackets. Because of these system inter-relationships, it’s not always easy to predict the resonances within a system, and so there’s always a little uncertainty as to where to start the troubleshooting process. These simple techniques may help quickly identify potential resonances within your system or product.

Continue reading…

Fig1 - Setup