EMC Shielding Demo

On 1/13/2015 Jerry greatly enjoyed demonstrating shielding effects and challenges to UIC students in Professor Danilo Erricolo’s class ECE 423 on EMC . http://www.ece.uic.edu/bin/view/ECE/ECE423

27 MHz Radio controlled toy car or 460 MHz FRS handi-talkies
were the sources and receptors sending their waves through a shielding “pot” and its variations . The car receiver was modified to excite an acoustical alert sounder, while the ordinary speaker of the handi-talkie “spoke” evidence of reception action.

First the lid , a single disk shield plate (far right in photo) , was held between the transmitter joy stick controller (in Jerrys hand) and the race car (red 2nd from right in photo ) . That was shown to be totally ineffective.
Thus one could initially hypothesize that radio waves at these frequencies do not behave like rays of light traveling in straight lines , to be blocked or reflected by “opaque” objects. Rather they behave more like acoustic or fluidic analogues flowing around ( diffracting ? ) or bouncing off other nearby objects.

Second , the solid metal open “cup-shape” or pot (in photo behind “shielding demo” white paper sheet) completely covered the race car with the open side facing away from the transmitter. It was also ineffective (for the same reasons) .

For maximum performance , one needs a fully enclosed “Gaussian shell” . It was demonstrated that huge shielding degredations occur from even Slight corruptions of the shell enclosure by modifying the fit / contact quality of the soup-pot lid against the pot opening. It was more remarkable at 460 MHz vs. 27 MHz.

A strainer version of the pot made of perforated metal (near Jerry’s hand) with ~5 mm diameter holes and using the same tight fitting lid , was effective at 27 MHz but largely ineffective at 460 MHz (why ? HINT Wave-guide beyond cutoff attenuation. Also handi-talkies have much more transmit power and receive much lower signal levels than 27 MHz toys , thus requiring more shielding attenuation to block transmission)

When an insulated ~12″ long wire penetrated a hole in the sealed strainer pot (as might be used to power the car within) , attenuation at 27 MHz was severely degraded. It acted like a receiving antenna to the transmitter outside the shield then the current it carried caused a re-radiated emission within the enclosure. However, when the wire was filtered with a sufficiently low impedance shunt capacitor, as a simple filter ( 2 nF not enough 10 nF enough) , shielding effectiveness was restored , as the current it was carrying was attenuated by diversion (bypassing) in to the shield structure.

Enjoy doing your own extensions and variations. Lets hear from you !

Jerry at JDM LABS 1/14/2015

Note : the inspiration for this demo was Dr. Amy Pinchuk of http://infieldscientific.com/eng/about.html
who demonstrated it at the IEEE EMC Society 2004 Symposium in Santa Clara .
Hey see you all in Santa Clara for the EMC Symposium this
March 16-20 http://www.emc2015usa.emcss.org/

JDM 1/23/2015

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JDM LABS 2013 Summary

Hello loyal fans & followers .
2013 has been a busy year for JDM LABS
As I popped into many tents along the midway I was treated to a lot of new and old situations . Here’s a brief overview of what went on.

** Corrected FCC Part 15 Radiated Emissions issues in VHF range on consumer product, used for linking Wireless acquired data to the Internet.
* FIX = Discrete Common-Mode choking / isolation of device from its connection to AC mains power source .
* Start-up company – housed in a Midwest University Industrial Park Incubator using KickStarter funding model.

** Reduced Radiated & Conducted Emissions in LW, MW & VHF ranges of in-vehicle 10 kW class AC mains battery charger.
* FIX = Extensive common-mode filtering on all I/O , plus external cable shields, plus careful routing of internal wiring to minimize coupling to near-field noise sources.
* Well established North-East power-conversion company adapting new technologies to new markets.

** Performed Design Review and bench-top analysis of “interface tool” to connect in-vehicle data busses to maintenance service tools.
* ACTION = Identified HF & VHF emissions risks & mediation approaches. Recommended PCB improvements.
* Medium sized South-East region specialty transportation electronics company, a repeat Client.

** Performed Design Review and Bench-Top Radiated Emissions analysis & mitigation identification on “manufacturing cell” using multiple VFD / Servo BLDC motor controls. Issues in the LW, MW and VHF regions affecting EU requirements.
* FIX = multiple common mode “cores” on all internal communications and power distribution cables . Ground-bond “clamps” on all external shielded motor cables.
RF gasketing of metallic enclosure seams & doors. .
* Large multinational company, headquartered in Midwest.

** Identified and reduced radiated emissions in HF & VHF regions from serial buss of battery monitor electronics for electric motor augmented personal-transportation.
* FIX = Common mode choke in serial data port .
* Small Midwest start-up, seeded by University researchers, using on-site manufacturing.

** Identified cause of Radiated Emissions in UHF region, from “Jumbo-tron”-like color LED image display. Worked on-site outdoors at a Midwest hotel.
* FIX = Firmware micro-code modification to attenuate specific signal components.
* Medium sized international company, experienced in large custom commercial LED image color displays.

** Advised methods & techniques to reduce radiated emissions in LW MW & VHF regions from portable 50+ kW class Diesel Electric generator source.
* FIX = Multiple discrete Common Mode filter elements on key circuit nodes.
* Medium sized Midwest company with a long history of locally manufactured generator-sets for transportation & military applications.

** Identified cause of UHF region RF Field immunity weakness in consumer vehicle entertainment media hub.
* FIX = PCB re-layout optimizing effectiveness of existing Common-Mode filtering elements.
* Midwest division of large multinational component & sub-assembly maker.

** Identified mitigation techniques to improve HF-VHF RF Current Immunity of off-road vehicle access control system.
* FIX = Cable Common-Mode ferrite choking.
* Medium sized Midwest company well-established in off-road vehicle support electronics.

** Identified & reduced RF emissions in LW-MW & VHF regions from switch-mode supply in LED illumination system for heavy vehicle applications.
* FIX = PCB layout optimized to minimize coupling of Differential-Mode signals into Common- Mode structures.
* Medium sized Midwest company with niche expertise in vehicle LED lighting systems.

====Recent Education Services ===
* Completed IEEE EMCS Distinguished Lecturer tour 2011-2012 . Informed & entertained & chapters in Austin & Dallas TX, San Jose CA, Madison WI, Detroit MI, Montreal & Ottawa CAN, Chicago IL.

* Developed and presented Lecture and Hands-on Laboratory on Cables & Shielding , supporting “Introduction to EMC SC071″ a 1.5 CEU continuing education course at Illinois Institute of Technology (IIT). Acting as adjunct Teaching Assistant with fellow IEEE EMC Chicago Chapter colleagues.

*Completed 3rd year of IEEE EMC Society Workshop & Tutorial on
” EMC Consultant’s ToolKit” at the Annual International EMC Symposium
in Denver Colorado. Co-presenters were Key Wyatt of Wyatt Technical
Services http://www.emc-seminars.com , Patrick Andre’ of http://www.andreconsulting.com
and Dr Tom Van Doren, of The Van Doren Company http://www.emc-education.com/.

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EMC MiniSymposium – May 7 – Chicago

Hello All : I want to alert you to a great education and networking event.
For those of you who cannot get to the “big” EMCS annual Symposium,
we’re bringing it home to you, Chicago Style .

15th Annual Chicago IEEE EMC MiniSymposium
Tuesday May 7, 2013
Itasca Country Club, 400 East Orchard, Itasca, IL 60143
Convenient to IL-53 / I-355


“Fundamentals of EMC”

“Critical Infrastructure and the Potential Impacts ,
HEMP EMP IEMI and Geomagnetic Disturbance”

“Very-Near-Field Solutions for Far-Field Problems”

“How Coaxial Cables behave in EMC Environments”

“Multi-Tone Radiated Immunity per IEC Standards
Cut your test time in half (or more)”

NEW ! afternoon parallel segment :
“Hands-on Experiments and Laboratory Demonstrations”
Sponsored by Chicago’s own Education Committee

Your Very Affordable Full Day Program Includes :
Lunch, Breaks / Snacks.
20+ Equipment & Services Vendor / Exhibitors.
Professional Engineers (PE’s) 4 PDH credits
Attendance Certificate
Printed Presentations Booklet.
Valuable Prizes – Drawings, Raffles, EMC-Opoly

We look forward to seeing you at our 15th annual event !
– Frank Krozel, MiniSymposium Chairman –

Advanced Program http://www.emcchicago.org/adv.pdf
Attendee sign-up form http://www.emcchicago.org/aform.doc
Vendor sign-up form http://www.emcchicago.org/vform.doc

Exhibitors and Vendors signed up as of 4/14/2013

Electronic Instrument Associates Central, Inc.
Elite Electronic Engineering
EM Test
DLS Electronic Systems
IEEE EMC 2013 – Denver
EMI Solutions
Associated Research
HV Technologies
TRS Rentalco
Fair-Rite Products Corp
API Technologies-Spectrum Control
Teledyne LeCroy
VTI / Vacuum Technologies lnc.

Please check for additional details and updates

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Ghosts In The Machine ?

March 22, 2013 . Dothan GA .
After eating dinner , our 2012 Ford Fusion, with doors still locked,
somehow had fully opened driver and passenger door windows and tipped open the sunroof.
This was depite using the keyless entry fob to lock doors and hearing the acknowledge
“horn beep” after arming the security system !!

Do not think its an “EMC problem” ..
Could there be a keyless entry command to open the 3 (of 5) windows
yet keep doors locked ?

Then , its SYNC info-tainment system is “powered by uSoft” & uses Bluetooth .
Any known HACKS for the Bluetooth pathway in ?

Automotive buss architects claim there are no physical connections
between critical comand & control systems and auxillary or option feature buss’.
But I heard tales of buss hubs, portals & bridges for the convenience of design & development ? hummmm

** For more discussions of vehicular electronics “ghosts” see :

LinkedIn Group *EMC Experts*
“Auto Unintended Acceleration still in the news”

“Is Toyota Telling the Truth About Sudden Acceleration?”

OK I’m embarassed – its the old “read the manual” Lesson-Learned 😉
Describes the “global open” function: Hold down the unlock button for 5 seconds.
An easy to explain scenario from mashing keys in pocket or purse. Need to have dealer de-program the “feature” . Thanks to Chris Armstrong of LinkedIn “EMC Experts” for getting it. Now back to our regularly scheduled EMC stories .

Jerry at JDM LABS

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DIY Current Probe Comparison

Hey Everyone . Ever balked at paying $100’s for a “regulation” RF current probe ? Well here’s a comparison between a DIY probe made from a clamp-on ferrite vs. a commercial one by Fischer (FCC) . Thanks to Colleague Ken Wyatt http://design-4-emc.com/ for loaning me his FCC F-33-1 probe.


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EMC Training = Chicago MiniSymposium

Thought you would like to get a day of great & affordable EMC Training .  Just $35 for IEEE members includes generous Lunch & break snacks. Over 20 Exhibitors of the latest EMC equipment, components, software  & services.  Enjoy our EMC-opoly game with prizes as well as  periodic raffle drawings.  A great day of learning & Networking !  See you there !

Tuesday May  8  14th Annual Chicago EMC MiniSymposium  
(Itasca Country Club,  400 East Orchard, Itasca, Il. 60143)          http://www.emcchicago.org/    

 Attendee sign-up   http://www.emcchicago.org/sectfiles/aform.pdf  

Programme :    7:30     Registration
8:00     Welcome – Frank Krozel
8:15     “Fundamentals of EMI / EMC”  – Tom Braxton, Shure Incorporated
9:15     “Tips / Techniques for making EMI measurements with a  Spectrum Analyzer  and Test Receiver”   Lee Hill, Silent Solutions
10:15   Break / Vendor tabletops  

11:15   “Conductive Plastics” – John Perkins, Parker Hannifin
12:15   Lunch
12:45   Break / Vendors
1:30     “The Hype Surrounding the BiConical/LPDA Hybrid Antennas”   – Zhong Chen, ETS-Lindgren 

2:30     Break / Vendors
3:30     “PCB Layout Details for Reduced EMI Issues”
         – Roger Swanberg, DLS Electronic Systems
4:30     “Testing Smartgrid and other Emerging Technologies”
          – Jason Smith, HV Technologies
5:30     Symposium concludes

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All About EMC Consulting – Save The Date

Hello loyal followers.

Its been a while , Life sometimes gets in the way. But I want to share news of a great upcoming event in Long Beach Ca. The IEEE EMC Society annual International Symposium  August 14 thru 19 . Particularly the Friday afternoon Workshop : “EMC Consultant’s Toolkit ”  FR-PM1  http://www.emc2011.org/assets/files/Workshops&Tutorials.pdf

Its important because many companies cannot afford a full-time / on-staff skilled EMC expert to guide or remediate their designs, especially in this economy.  Thus there is a huge opportunity for consultants to help companies on an as-needed basis. The session addresses practical tools & skills across technical , business & interpersonal domains. 

We’ve assembled a world class team with over a century of combined experience. I’m doing the intro & leadoff “Marketing Yourself” . Then Kenneth Wyatt of http://www.emc-seminars.com/index.html  covers “Practical Troubleshooting & Using Social Media” . Henry Ott of http://www.hottconsultants.com/news.html who is a pioneer of EMC consulting in the USA will spin “War Stories” which both teach & entertain.  Patrick  Andre’ of  http://www.andreconsulting.com/  will address”Presenting Yourself Professionally” . Then Daryl Gerke of http://jumptoconsulting.com/ will answer that question ” So you want to be a consultant?” . Finally all 5 of us will do a panel discussion taking questions from the audience.

So if you have questions for the panel please submit them here & we’ll make every effort to cover them. If it is very time sensitive we’ll get you the answer sooner .

So hope to see you in Long Beach  or we can dialog right now !  

I’ve been helping out a number of clients and the <generalized> case studies will appear here in the coming days & weeks.

Best Regards,  Jerry

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