Below are the questions asked during the live event, along with their respective answers.

Q: Where do you see simulations being useful for automotive EMC compliance?
A: Building off EMC LIVE for Automotives Keynoter Todd Hubing remarks… ElectroMagnetic modeling simulations currently have limited benefits. It is not that the tools lack accuracy or precision or even speed. But rather, because one must have significant knowledge/experience/insights
to define the problem with sufficient accuracy and completeness. To know what to include that is most important to the phenomena of greatest interest and exclude too much fine detail which will burden the computation without giving a better answer.

As Todd and other trusted colleagues have taught: Posing the right / best question is the most important part at the start of the simulation problem set-up process. You get an answer to what you ask. As the old GI-GO garbage in – garbage out. If you ask the wrong question then the answer is not useful to the real problem or the dominant mechanism.

A-I, Artificial Intelligence as being furiously applied to self-driving cars and may advance in time, to break down the EMC problem well enough to identify and solve the most important dominant issues of the problem. Till then we need H-I Human Intelligence & insight to identify the most significant elements of the EMC performance short-fall and the causal structures and active devices.

Near term, DRC, Design Rule Checking, is available in commercial tools as stand-alone or add-ins to PCB design (for example). If the Rules are sufficiently detailed and fit well to the kind of design being done, a sort of “80-20 rule” benefit may be available. For the effort of creating or adapting a rule set to your design, it may identify 80% of the issues needing correction & adjustment. Leaving a tougher 20% of the design issues to be manually discovered and corrected. That should reduce the number of design spins/turns/iterations with a desirable economic and time benefit, as well as improving the customer-perceived quality of the design and lowering the fatigue of design team members. Over time the DRC’s can be refined from the application experience and creep toward 90-10 or even better.

After the EMC-LIVE event, I heard the ANSOFT CEO Ajei Gopal’s Keynote to “Simulation World” symposium My EMC take-away from his vision is that CAD / CAE tools are the best path to better design. Maybe in our lifetimes, simulation will advance in EMC as well . Note, EMC does have a powerful market-force / advantage that may drive / advance simulation! There are standards, regulations, and government enforcement authorities who require EMC compliance to be able to sell a product. Thus design organizations will quickly learn that they cannot cost-effectively “test the quality/conformance into the product”. So they will be reaching out for EMC design tools to make it “right by design” much like the IC design world has, of necessity, developed their CAE design process.

I could go on and on but this is a start. Thanks for the question & the forum.

Q: What is the radiated immunity considerations for the big PCBs like cluster?
A: If you mean a “vehicle dashboard instrument cluster “…
They can have
1) mechanical moving rotary needles
2) virtual LCD creating images of moving needles or thermometers & bar graphs
3) a mixture of the two technologies.

In any case “size matters” relative to radiated immunity. Consider the overall dimensions of the PCB width and height. When those are near the size of a half-wavelength of the excitation frequency. (Or a full wavelength or integral multiples of the “critical” or Eigen frequency.) They become efficient antennas to absorb the wave. Then they deliver significant RF signal current across all the components on the PCB. The current may be “interestingly distributed” in intensity and locations across the PCB due to other modalities of the resonant structures. So do not be surprised if different circuits are upset at different frequencies. Just part of the resonant structures… In any case, Upsets are likely! So find the weak affected components or subsystem or IC’s and apply the “usual” EMC fixes to their sensitive “ports”. It is likely not practical or cost-efficient to shield the entire cluster in a metallic box. Besides its face to the driver has to be optically transparent. In some industries, such a clear face can be EMI conductive coated but it is $$. And ALL the wires passing through the shield must be filtered to make it effective as a system.

Also, not to ignore the (antenna) wires/cable harness hanging off the cluster. They have their own resonant wave-length like any ECU (electronic control unit) product. So the radiated wave will efficiently be captured at those “critical” frequencies and send RF current into the product to flow across the PCB into affected sensitive circuits… It’s tough to stop the RF coming in the wires. Sometimes a series ferrite loss device in specific wire(s) of the bundle can reduce the current to a level below the sensitive circuit threshold. And sometimes not… “It depends”. But like the direct radiation on to the PCB, the approach can be the same.
Likely the Henry Ott “dominant mechanism ” is in the sensitive circuit. There apply “fixes ” to lower the amplitude of the RF signal entering it.

Also, the combination of cable plus cluster forms a wire antenna with a “capacitive top hat”. Meaning, there is yet another resonant mode where the effective wavelength of the wires is increased by the “capacitive top hat”, producing another set of critical frequencies to absorb the RF and efficiently conduct it into the PCB and sensitive circuits.

So the big takeaway about identifying sensitive or critical or resonant mode “Eigen” frequencies: Don’t spend a lot of effort calculating or estimating the dimensional related frequencies.
Even if you have a 3D ElectroMagnetic CAD tool that “automagically” gives the Eigen frequencies, the quality of the structure description will not be complete enough to cover all the practicalities of a real cluster plus cable. My opinion: There will be little benefit to importing the PCB CAD file plus housing plus cables. It’s just too all complex and loaded with unknowns and variances relative to an actual DUT ( device under test) EMI lab setup of cluster plus cables plus… But do be aware during testing, that there will be critical upset frequencies in the range of the mechanical dimensions, but also at unusual frequencies offset from those “first-order” predictions.

So “at the end of the day” (as attributed to Irish Pub conversations) the upset circuits will need appropriate local fixes that work over a wide range of upset frequencies.

There are also PCB system-level fixes and design practices that can be globally helpful. Such as optimal choices of PCB layer stack-up… as taught in Henry Ott’s ” EMC Engineering” Chapter 16 and other fine sources. As always, “It depends”, but it’s not a total shot in the dark if we keep our cool and follow the basic physics. Happy EMC Hunting!