Electronic Environment no 4 2015

Page 1

A REVIEW OF THE PRINCIPAL EMI COUPLIG PATHS The key to undestanding and preventing or solving EMI problems Part 1: Conduction Paths


The ten commandments for EMC, part 3




It will be a robot for Christmas relentlessly, either we’ve planned for it in our calendars or not. I will, as usual, elaborate a little on the Swedish phenomenon “Christmas gift of the year” in this column. The Swedish retail research institute (HUI) announces every year what they expect to be “The Christmas gift of the year”. It will, not surprisingly, be an electronic gadget again. This time it´s loaded with exciting features, such as being rechargeable and automotive: A robot vacuum cleaner!


of the first robot vacuum cleaners for the Swedish market almost 20 years ago. So this year’s Christmas gift of the year has indeed been biELECTROLUX LAUNCHED ONE

ding its time, awaiting its great (?) break-through. The current models are doing a far better job than their predecessors, according to a Swedish test site, which has tested robot vacuum cleaners now and then through the years.

pected to pave the way for. Sweden is one of the leading nations in the world when it comes to the development of 5G and this paradigm shift means considerable new possibilities of economical growth. increase in wireless technology in the fully connected society will, however, increase the complexity and the vulnerability and thereby result in further challenges within Internet security and electromagnetic interference signals. THE COMING MASSIVE


Miklos Steiner presents part 3 of The Ten Commandments for EMC in the The Eye On series, which focuses on shielding. Michel Mardiguian presents problems and solutions regarding coupling paths and talks about the importance of understanding the coupling mechanism. Peter Stenumgaard explains visions and challenges for the socalled networked society, the fully connected society, which 5G is ex-

interesting program for those who work in some of our electronics disciplines. go in parallel with the SEE fair at Kistamässan and the event will be a very exciting venue. You can buy conference tickets right after the year-end. EEC 2016 WILL

I wish you all a very Merry Christmas and a Happy New Year!

for Electronic Environment Conference 2016 is soon ready and will be presented shortly at electronic.nu. We will, as usual, present a very THE CONFERENCE PROGRAM



• Shielded secure meeting rooms • Turn key shielded and anechoic chambers • Shielded rooms for data security • Shielding materials for self-assembly: doors, windows, absorbers, ferrites, filters, gaskets and metalized textiles. • Shielded boxes for GSM, DECT, radio testing etc • EMC testing services in our own lab.




Electronic Environment is published by Just Rivista AB Mässans gata 14 SE-412 51 Gothenburg Tel: +46 31-708 66 80 info@rivista.se www.rivista.se Address Changes: info@justmedia.se


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Technical Editors: Peter Stenumgaard Miklos Steiner Michel Mardiguian

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Print: Billes, Mölndal, 2015 Contents may not be reproduced in any form without the prior consent of the authors. While every attempt is made to provide accurate information, neither the publisher nor the authorsaccept any liability for errors or omissions.

Content, Electronic Environment 4.2015 Eng


Joint IEEE International Symposium on Electro magnetic Compatibility and EMC Europe, Dresden 2015




The Eye On Serie: The Ten Commandments For EMC, Part 3

Conferenser and courses



A Review of the principal EMI Couplig Paths


The Networked Society


Do we really need the EMC requirements?

The key to undestanding and preventing or solving EMI problems. Part 1: Conduction Paths

A Vision That Requires Strategic Choices


Michel Mardiguian

Peter Stenumgaard FOI Gick Teknisk Fysik och Elektroteknik LiTH -1988, Tekn. Dr. Radiosystemteknik, (KTH 2001). Han arbetade fram till 1995 som systemingenjör på SAAB Military Aircraft, där han arbetade med elektromagnetiska störningars effekter på flygplansystem. Detta inkluderade skydd mot exempelvis blixtträff, elektromagnetisk puls (EMP) samt High Power Microwaves (HPM). Han har varit adjungerad professor både på högskolan i Gävle och Linköpings universitet. Peter arbetar till vardags som forskningschef på FOI. Han är specialiserad på elektromagnetiska störningars påverkan på trådlösa kommunikationssystem. Han var technical program chair för konferensen EMC Europe 2014 Miklos Steiner Miklos har elektromekaniker- högskoleutbildning för telekommunikation och elektronik i botten samt bred erfarenhet från bl a service och reparation av konsumentelektronik, konstruktion och projektledning av mikroprocessorstyrda printrar, prismärkningsautomater, industriella styrsystem och installationer. Miklos har sedan 1995 utbildat ett stort antal ingenjörer och andra på sina kurser inom EMC och är också författare till den populära EMC-artikelserien ”ÖGAT PÅ”, i tidningen Electronic Environment. Under många år var Miklos verksam som EMC-konsult, med rådgivning och provning för många återkommande kunder. Mångårig erfarenhet från utveckling av EMC-riktiga lösningar i dessa uppdrag har gett Miklos underlag, som han med trovärdighet kunnat föra vidare i sina råd, kurser och artiklar.

Michel Mardiguian, IEEE Senior Member, graduated electrical engineer BSEE, MSEE, born in Paris, 1941. Started his EMC career in 1974 as the local IBM EMC specialist, having close ties with his US counterparts at IBM/Kingston, USA. From 1976 to 80, he was also the French delegate to the CISPR. Working Grp on computer RFI, participating to what became CISPR 22, the root document for FCC 15-J and European EN55022. In 1980, he joined Don White Consultants (later re-named ICT) in Gainesville, Virginia, becoming Director of Training, then VP Engineering. He developed the market of EMC seminars, teaching himself more than 160 classes in the US and worldwide. Established since 1990 as a private consultant in France, teaching EMI / RFI / ESD classes and working on consulting tasks from EMC design to firefighting. One top involvment has been the EMC of the Channel Tunnel, with his British colleagues of Interference Technology International. He has authored 8 widely sold handbooks, two of them being translated in Japanese and Chinese, plus 2 books co-authored with Don White.

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CONFERENCES & EXHIBITIONS EMV 2016 February 23-25, Düsseldorf, Germany INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY February 29, Florida, United States

ISQED 2016 (QUALITY ELECTRONIC DESIGN) March 14–16, Santa Clara, United States GEMIC 2016 – GERMAN MICROWAVE CONFERENCE March 14-16, Bochum, Germany EXPOELECTRONICA 2016 March 15-17, Moscow, Russia


IOT SUMMIT March 17–18, Santa Clara, United States



MICROWAVE & RF March23-24, Paris, France

EDI CON CHINA 2016 April 19-21, Peking, China

APEMC 2016 May 18, Shenzhen, China


EUROPEAN WIRELESS 2016 May 18, Oulu, Finland

S.E.E. April 19–21, Kista, Sweden 2016 IEEE RADAR CONFERENCE May 2-6, Philadelphia, United States

INTERNATIONAL MICROWAVE SYMPOSIUM 2016 May 22, San Francisco, United States 2016 ESA WORKSHOP ON AEROSPACE EMC May 23, Valencia, Spain

SVIAZ-EXPOCOMM 2016 May 10, Moscow, Russia POWER CONVERSION INTELLIGENT MOTION (PCIM) 2016 May 10, Nuremberg, Germany

Vi tar tacksamt emot tips på kurser, föreningsmöten och konferenser om elsäkerhet, EMC (i vid bemärkelse), ESD, Ex, mekanisk, termisk och kemisk miljö samt angränsande områden. Publiceringen är kostnadsfri. Sänd upplysningar till: info@justmedia.se. Tipsa oss gärna även om andras evenemang, såsom internationella konferenser!


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Engelsk annons Electronic Environment nr 3 2015.indd 1

2015-09-09 13:52:49

Electronic Environment 4.2015 Eng

The Eye On Serie What everyone should know about EMC:

The ten commandments for EMC, part 3


Shielding is one of the concepts associated with EMC. Often, for example, mechanical engineers are tasked to build a shielding box, without further specification of ie operating frequencies or desired attenuation. How much attenuation is reasonable to expect? Here are some rough reviews of shielding levels:

• 0 - 10 dB: insignificant shielding • 10 - 30 dB: minimum threshold for meaningful shielding • 30 - 60 dB: intermediate shielding • 60 - 90 dB: good shielding • 90 - 120 dB: very good shielding. (120 dB is extremely difficult to achieve.)

The task of the shielding is to create a zone whose electromagnetic environment differs from the environments outside the shield. Inside the shielded space (sometimes called Faraday’s cage.), for example, a circuit can work undisturbed, ie without being affected by an incident electromagnetic field. The shield is effective in both directions and also attenuates the energy leakage from the circuit inside out. Note that such an ideal shielding box does not have any openings, slots or connectors. It floats freely and is completely sealed, no leakage. Only electrically conductive materials are suitable for shielding electromagnetic fields (see Figure 1). The better the conductivity is, the more effective is the shield. In general, homo-


geneous plates of all common metals have good enough shielding effectiveness (SE) in most frequency ranges. The exception is for low frequency magnetic fields, where most metals have low SE. For frequencies below about 10 Hz, metals of high relative permeability provide effective shielding. To attenuate fields in the frequency range 10 - 1000 kHz thick metal with good conductivity, ie aluminum or copper, is needed.

that pass through the shield without measures. In the next article we will take a look at the difficulties and pitfalls. Miklos Steiner miklos@justmedia.se

A wire mesh has almost as good SE as a homogeneous plate provided that the stitches are small relative to the current wavelength. The denser meshes the higher damping. Shielding effectiveness (SE) (see Figure 1 and 4) of metals can be divided in two main contributors: Reflection attenuation (R) (see Figure 2), and Absorption attenuation (A) (see Fig. 3). It’s not so easy to design a shielding box (see Figure 1) as many designers seem to belief. By my experience a lot of resources (money and time) has been invested on shielding, sometimes for too little benefit. Trying to build or buy expensive so-called ”EMC proof” enclosures would not help if you leave all the cables and wires

Figure 1. Shielding EA01 SE = R+A [dB] SE = shielding effectiveness R = Reflection A = Absorption

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Electronic Environment 4.2015 Eng

Figure 2. Reflection Attenuation EA02 Reflektionsförlust = reflection attenuation r = distance from the source to the shield Elektrisk fält = electric field magnetfält = magnetic field planvåg = uniform wave (plane wave) Frekvens = Frequency

Figure 3. Attenuation by absorption EA03 Skärmplåt = Shielding plate Figure 4. Total shielding effectiveness (SE) EA04 Elektrisk fält = electric field magnetfält = magnetic field planvåg = uniform wave (plane wave) Frekvens = Frequency Image Sources: Web course.


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Electronic Environment 4.2015 Eng

General-purpose power-quality monitor for on-site testing and troubleshooting

Precise detection of frequency-agile signals and bursts

The Yokogawa CW500 power quality monitor, a general-purpose unit for field and on-site testing and troubleshooting, is the latest addition to the company’s range of power measuring instruments.

The IZT GmbH launched a new option for its powerful R4000 RF receiver. The 32768-point FFT option in combination with the 120 MHz real-time bandwidth ensures reliable detection of fast bursts and frequency-agile signals. Even the most advanced hoppers with extremely high hop rates are detected under demanding SNR environments. The Hopper Detector plugin provides real-time information about detected hoppers containing bandwidth, dwell time and time-of-arrival information.

Featuring a range of clamp-on current probes, built-in data logging and measurements conforming to the IEC 6100-4-30 Class S standard, the CW500 is a multifunction instrument designed to aid the inspection and maintenance of power quality in factories, commercial or public facilities. In particular, it will detect, measure and record events such as voltage swells, sags, dips or interruptions, inrush currents, harmonics distortion and flicker which can have an adverse effect on equipment operation or energy efficiency. The 4-channel instrument can measure multiple power lines in configurations from single-phase/2-wire up to 3-phase/4-wire, and will simultaneously measure AC voltage input on three channels, current input on four channels and DC voltage input on two channels. Parameters measured include the instantaneous, average and maximum/minimum values of voltage, current, DC input voltage, power, power factor and phase angle, along with phase advanced capacitance calculation. The CW500 operates over an input AC voltage range from 6 to 1000 V and a DC voltage range from 100 mV to 10 V. The current ranges are from 2 A (for leakage current only) to 3000 A, with intermediate ranges of 50A, 100A, 200A, 500A and 1000A depending on which dedicated clamp-on current probe is used. Accuracy for power measurements is 0.3% of reading. Up to 2 Gbyte of memory is provided by an SD memory card, and communication is via a USB interface which allows real-time management of measurements. Built-in PC software (CW500 Viewer) provides analysis of recorded data and report generation including automatic graph creation, as well as simple management of the main unit settings.

Using the 32768-point FFT, the real-time frequency resolution is less than 5 kHz over the full 120 MHz bandwidth. The transformation is processed in a high-performance FPGA. The continuous detection without any gaps makes the R4000 a very powerful real-time signal analyzer. In parallel to the PSD (Power Spectral Density), IQ content of subbands or even the full bandwidth can be retrieved and forwarded to the sensor controller. This allows to detect and analyze thousands of signals in parallel. Utilizing the 4096-point FFT option, the time resolution of the spectrum can be as fast as 25.6 µs per spectrum. This is orders of magnitude faster than swept analysis techniques and meets the demand for systems being able to capture today’s hopping, transient signals. The IZT R4000 delivers a powerful digitizer, wideband receiver and signal collection system for COMINT and ELINT systems, wideband satellite surveillance and continuous broadband radio signal recording. It achieves an instantaneous bandwidth of 120 MHz and covers a frequency range of up to 18 GHz.

Source: IZT

Källa: Yokogawa

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Electronic Environment 4.2015 Eng


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Electronic Environment 4.2015 Eng


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Electronic Environment 4.2015 Eng

A REVIEW OF THE PRINCIPAL EMI COUPLING PATHS The key to undestanding and preventing or solving EMI problems

PART 1: CONDUCTION PATHS As briefly described in our introductory Article N°1 ( Issue #2-2015 of EE Magazine), ElectroMagnetic Interference is a Source/Coupling Paths/Victim situation, the basis for an overall understanding of EMI control in order to reach a satisfactory level of compatibility (EMC). We also said that reducing the interference at the source itself, or at the victim’s levels, were most of the time unpractical. Therefore, the only remaining area for action is in general the coupling path, which implies understanding the coupling mechanism. PREAMBLE This article and several of the 10 articles to come will focus on the essential EMI coupling mechanisms: - Understand them qualitatively, with sometimes a calculated estimate helped by simple numerical examples of real cases. - Prevent them by proper design guidelies (or fix them if too late..) We will start by paying attention to Susceptibility / Immunity cases, since it is often the engineer’s main concern, even if this is questionable. Then we will naturally address Emissions problems, which will become easy because ALL the EMI mechanisms are reversible. 1. THE FIRST OF THE CONDUCTION MECHANISMS: COMMON IMPEDANCE COUPLING 

Figure 1. The source-and-victim concept, a basis of EMI/EMC strategy. Your equipment can be the victim, or the source.

As shown on Fig.1, interference coupling paths can be grossly divided in CONDUCTION and RADIATION. Why and how is this sorted-out? This is purely arbitrary since no current can flow without creating an associated electromagnetic field, and vice-versa, any electromagnetic field is causing voltage and/or current to appear in exposed conductors. However: - up to a few MHz (say < 10 MHz) conduction coupling dominates EMI problems, because at such frequencies, typical equipments, internal circuits sizes and external cables lengths are << λλ. Remember, wavelength and frequency are related by: λλ(m) = 300/F(MHz). Think that a 1.50m cable length represents only λ /20 at 10MHz, and λ /200 at 1MHz, making it a very unefficient antenna for radiating undesired signals. - Conversely, as frequency increases above tens of MHz, cables and circuits dimensions tend to represent a progressively larger fraction of wavelength. Our 1.50m cable now represents λ /6 at 30MHz, where it starts acting as an efficient – although fortuitous, antenna, causing conducted noise to significantly radiate. The present article will address the first, and major conduction mechanism: Common Impedance Coupling (CIC) is altogether the most easy to understand and calculate when needed, probably one ranking highest on the scale of EMI problems in a system life …. and not necessarily the easiest one to solve because it may involve grounding at all levels: functional, safety or structural. Two important facets need to be remembered here: • One is that most common schematics simply address the functional behaviour, representing only DC or low frequency circuits, while real life circuits contain high frequency elements that are seldom exposed. • The second is that the term ”ground”, widely used for many applications, is often trusted as a stable reference, while many times it also

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Electronic Environment 4.2015 Eng

acts as a current return path, of which the characteristics shall be documented, since it will be used by HF currents that won’t follow the classical DC electrical schemes. A basic scheme for CIC is shown on Fig. 2 with a frequent cause of interference, where a great variety of circuits/ equipments/ systems are sharing all or part of a common conductor. Here a pulse-driven motor and an analog sensor circuit are sharing a same return wire. Problem arise because of the RxI, or more generally the ZxI product in the shared segment A-B. The conductors that are typically shared in common by several circuits are power distribution wires/busses and return, or reference conductor. The latter is, by far, the most frequent of multiple-user cases, as with: - functional return wire, for inst. the (-) wire or Neutral wire in dc or ac power distribution - safety conductor ( Green/Yellow wire) - structural part used intentionally as power return, like in cars, some aircrafts etc … - the earthing network in a building : real earth, buried earthing conductors etc …

cordingly, a corresponding Differential Voltage is found across the pair, or the load. - b) Currents coming from an outside source, are flowing on the two wires of the pair in the same direction, returning by the ground conductor (or ground, earth plane etc ..) is called the Common Mode (or ”unbalanced”) current. A corresponding Common Mode voltage is shown, as being the driving source. Needless to say, Common Mode voltages and currents are a major cause of EMI problems, since they often originate from invisble, nonintentional sources and follow invisible or non-intentional paths. 

Idiff VCM


Idiff Icm




30 Amp Figure 3. Conceptual view of Diff. and Comm. Mode currents.

+V Power Source





Figure 2. A basic, very common case of Common Impedance Coupling (CIC)

Looking at Fig.2, let us assume the power and signal circuits have the following characteristics: - Motor current pulses amplitude : 30 Amp peak, average duration 1ms, risetime: 1µs - Detection threshold of Analog monitoring loop: 5mV The 2.5mm wire has a 5mm2 cross section and a 3.5mΩ/meter dc resistance. The simple I x R product of the pulsed current along the 3m return wire is: 3.5mΩ x 3m x 30A ≈ 300mV This 300mV ground wire shift between points A & B appears as an error voltage in series in the analog sensor loop, whose sensitivity level is only 5mV. This is a very bad EMI situation where the noise level overrides by 60 times the detection level of the victim.

2. BASIC RULES FOR REDUCING COMMON IMPEDANCE COUPLING (CIC) Back to our problem of Fig. 2, we can now say that the A-B voltage difference on the common return conductor is a Common Mode (CM) voltage pushing a small % of the motor current in the analog sensor circuit. For reducing this CIC coupling, we must act on the Z x I product, that is reduce Z or reduce I. This is the basis of all the solutions we will shortly describe, summarized in a few simple rules: Rule 1: do not allow large currents (more exactly large ∆I/∆t) to flow in the return or reference conductors of sensitive circuits. Rule 2: when several circuits are sharing a same reference or power distribution conductor, try making it as equipotential as possible, by lowering its impedance Z Applying Rule #1 means segregating the current paths, by allocating dedicated conductors to different families of circuits, such as heavy currents will not flow in the same wires or traces as sensitive circuits return. This is the basis of the star distribution or single point grounding schemes. Notice that the principle applies to the (+) dc, (or phase) conductors as well, if several consumers are sharing the same power source.

But there is more than this: the 0.3V is just a resistive dc voltage drop. Taking into account the self-inductance of the return wire, we must 3. BENEFITS AND LIMITATIONS OF STAR (OR SINGLE COMadd the inductive kick during the 1µs rise time of each current pulse: MON POINT) DISTRIBUTION A common way of applying Rule #1 is the star distribution principle of ∆V = L∆I/∆t, where L is the self-inductance. Fig.4(a). Functional circuits in boxes A and B are supplied by dedicated power leads, and referenced to their local ground. Thus, power supply Ordinary round wire with diameter in the mm range have self-inductance current returning from (A) cannot contaminate the power return wire of about 1.2µH per meter, that is 3.6µH for our 3m segment. Thus: of (B) etc…. . We commonly say that we have avoided a Ground Loop.  6 6 ∆V = 3.6.10- H x 30A/ 1.10- = 100V So, not only we have a recurring 0.3V offset that is corrupting the sensor analog signal, but on top of it, a 100V spike appears at every current front, that can damage the analog amplifier input. At this point, we need to introduce the term ”Common Mode” voltage or current, a key definition which is the crux of many EMI manifestations and solutions. The simple circuit on Fig.3 shows a wire pair carrying two sorts of currents: - a) the intentional current flowing towards the load then back to its source is called Differential Mode (or ”balanced”) current. Looking across the wire pair, the amplitude difference between the upper and lower wire opposite currents is null, since it is the same current. Ac-




Power Supply 0V


Figure 4. (a) Practical application of Rule #1 (current segregation) by star distribution

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Rule #5: Boxes at the ends of a star network must not exchange directly signals, except through isolated links

ElectroMagnetic Interference is a Source/Coupling Paths/ Victim situation, the basis for an overall understanding of EMI control in order to reach a satisfactory level of compatibility (EMC).

On Fig.5 caption (b), we see an other case of defeating the SGP purpose and creating a ground loop. Box A and B are exchanging data by an ordinary signal cable. Each end of the link is referenced to its local 0v. Therefore, a new sneaky, parallel path is created for the return current of A to close back to SPG ”M” via the 0v wires in the signal link and the equipment B.

Idiff (A) 0V Power Supply 0V

Figure 4. (b) shows an other variation of Rule#1, where motor and sensor wirings has been re-arranged such as, starting from the power source, the current-hungry load is supplied first. Which leads to an addendum to the Rule #1, as Rule #3 below:

Doing so, the large ∆I/dt, going to and returning from the power source does not flow through the analog circuit wiring, hence causing no ∆V in the sensor-to-amplifier wiring. Finally an other option is shown on Fig.4(c), where a buffer capacitor has been added near the motor. The fast ∆I/∆t demands are supplied by the capacitor, acting as a local reservoir, self- recharging constantly from the battery, without creating pulsed noise on the common conductor A-B.




B (c)

Figure 4. (b),(c) Other practical applications of Rule #1 (current segregation)

A Signal Cable


Power Supply




Figure 5. Violation of the single point ground principle by (a): not isolating the Signal ground (0v) from chassis or, (b): interconnecting the 0v of boxes A and B via a signal cable. Some of the box A current, flowing through box B signal reference, is closing back to the Power Supply ground M.

Solutions to accomodate the above violations without creating ground loops are shown on Fig.6: On the power input side, a transformer is interrupting the primary loop, such as the designer has now the possibility to connect its electrical 0v to the equipment chassis. The I/O port where A and B are exchanging signals is equipped with small signal transformer or optical isolator which are restoring the necessary isolation, hence the SGP principle. 

Notice that in all these variations, we have not reduced the impedance of the return conductor. We have simply prevented large currents to flow in sensitive circuit reference. There is a strong constraint for the Ground Loop avoidance to work, that translates in two additional rules : Rule #4 : If Single Point Ground (SPG) is choosen, circuits (A) and (B), (C) etc … must have only ONE common node for their (+) and (-), at the power source To achieve this, the dedicated 0v references of A, B etc .. must be isolated from their local chassis if, as often the case, this chassis is locally grounded for safety or mechanical reasons. Violating this rule may cause circulation of some % of return current (A) in the 0v reference of (B), as seen on Fig.5.a).The resulting ground loop, easily checked with a current probe, is that some power supply return current of A is now crossing the 0v reference of B to return to M, the Power Supply SPG. This unwelcome current flow may disturb the operation of (B) sensitive circuits by Comm. Impedance Coupling.



Rule #3: when daisy-chaining a power distribution, always ensure that a) the device with highest current demand is closest to the power source, and b) the common segment shared by multiple fuctions is as short and low impedant as possible.



A 0V

Power Supply


Signal Cable


B Figure 6. Restoring the Single Point ground principle by a primary isolation device (Txformer or dc-dc converter) on power input, and by using signal isolation transformers or optical couplers on the I/O ports. Now, box A could have its 0v reference grounded to chassis, without creating an other ground loop.

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Electronic Environment 4.2015 Eng

4. HIGH FREQUENCY LIMITATIONS OF SGP (STAR) PRINCIPLE When we estimated the interference situation in the CIC example of Fig.2, we have found a ∆V of 0.3V + 100V spike appearing in serie in the common return segment A-B. However, this noise voltage does not fully appear at the amplifier input. We have to account for the divider ratio in the sensor-to-amplifier loop: Vinput = VA-B x 1000 / (300+1000) = 0.77VA-B

Figure 8. Principle of a multipoint grounding (MPG) , compared to SGP.

So, because of the high input resistance of the amplifier, practically ALL the CIC voltage appears at the amplifier input. Changing to an SPG (star) scheme, Fig.7 shows a dc/low frequency schematic: the ground loop seems now open at amplifier low side. The floating point E sees the CIC voltage at point B through an infinite impedance, and NO voltage appears at the victim input. The CM rejection VA-B /Vvictim is infinite. Yet, as frequency increases, no circuit can be totally isolated: the stray capacitance (Fig.7) let more and more current flowing in the isolation gap. At the same time, the impedance of the dedicated sensor grounding wire E-A increases, because of its self-inductance. Assuming a 30pF floating stray capacitance and 3.6µH for the 3m ground wire, the following Table 1 shows the progressive loss of ground loop isolation when frequency increases. Numbers indicate how much actual reduction is provided by the isolated sheme. At 10MHz and beyond, it is clear that the SGP becomes totally unefficient, not to mention a strong parasitic resonance at 15MHz. We will see in forthcoming articles how to cope with these limitations.. 

The price to pay is that this conductor must have a low enough dc resistance and HF impedance such as the resulting Z.I voltage could be tolerable for the most sensitive users of this shared ground. Unfortunately, above a few kHz, any linear (2-D) conductor: round wire, flat strap or braid, PCB trace, exhibit a self-inductance that will rapidly make it incompatible for acting as equipotential ground. Therefore we must change 1-D shape to 2-D shapes, like a plane or a grid. A large plane has practically no self-inductance (see Fig.9) if it is sufficiently large (no trace or wire near the plane’s edges), so it can be used for multipoint grounding of various elements. 

30 Amp

+V Power Source


D 300 Ω



1K Ω

30 pF 100 V 0,3 V



Figure 7. A low frequency representation assumes that the sensor ground E-A wire is practically a short-circuit, such as PCB 0v and power source 0v terminal are ≈ equipotential. But the E-A 0v return wire impedance increases as frequency increases, while the stray capacitance of the PCB makes the floating impedance E-B progressively lower.

Table 1. Ground Loop coupling with example Figure 7


Impedance of 30pF cap. Impedance of 3m wire









0.6.10 -2 (-44dB)

0.6 (-4dB)



CM rejection at pt. E

0.6.10 -4 (-84dB)

Peak voltage at Ampl. input


5. REDUCING CIC VIA MULTIPOINT GROUND We said before that reducing the Z x I product can also be achieved by reducing the value of shared impedance Z, and tying directly all sub-assemblies/equipments of a system to same return conductor. This application of Rule#2 means that we accept to mix all return currents in a same conductor (Fig.8).


Figure 9. DC resistance and HF impedance of various conductors. (A): copper layer 30µm thick, (B) ordinary steel sheet 1mm thick (Planes impedance given in Ω, or mΩ, per sq.area). (C, D) 1m long copper wire, respectively 6mm and 0.6mm. (E) copper strap 0.3 x 10 x100mm. Do not use graph values for frequencies F(MHz) > 60 / length.

This is what is done in multilayer PCBs, with Vcc and 0V copper planes, and in RF devices (Txmitters, Receivrs, amplifiers, mixers etc...) where the cast aluminium or zinc-plated box is normally used as the RF signal reference, including for connection of the coaxial cables.

SUMMARY ON COMMON IMPEDANCE COUPLING (CIC) • CIC is one major cause of conducted EMI problems. It can even contribute to Radiated EMI when a noisy ground excites I/O cables • The prime cause of CIC being a (Z x I) product, an efficient way to reduce it is by controlling I or Z. • Reducing I in a conductor shared by several very different classes of circuits implies managing the current paths, a most common way being the SPG (or star) distribution for power and ground. • The SPG becomes unefficient when the branching conductor length exceeds 30/F(MHz). • Multipoint (MPG) ground, achieving an equipotential reference is a better answer at any frequency, provided a good ground plane can be used (ex: PCBs). • If CIC cannot be reduced, other techniques like differential links, EMI filters, cable shielding can be used that allow an equipment to function even in the presence of a CIC. They will be addressed in forthcoming chapters, since they are a cure for many kinds of EMI coupling. Michel Mardiguian, EMC Consultant, France m.mardiguian@orange.fr

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An Editor’s Reflections

Dilemmas and EMC


ometimes EMC issues result in dilemmas where conflicting needs/ requirements need to be addressed. An actual example is window glass designed to have a certain degree of electromagnetic shielding effect. Such material may be desirable if one for various reasons does not want electromagnetic emission from the inside to propagate out from a building, or if you want to reduce the radiation of heat from the building.


he cause of the former can be both to not allow that someone outside exploits the signal, or not want the emission to disturb wireless systems outside the building. Windows with electromagnetic shielding effect reduces the amount of received electromagnetic signals into the building. This means that the signals from mobile telephone systems or other outdoor radio systems will be attenuated on the way into the building. This causes problems if one wishes to use such systems indoors.


ne such disadvantage can indeed be solved by creating slot antennas in the glass so that the mobile telephony signals or other signals within a certain frequency range will pass through. At the same time it is important to check if there is undesired emission from the inside in the same frequency range that will leak out through such slots.


epending on the needs one has for the activities indoors and what need there is to attenuate signals out of the building, this can be a difficult dilemma. EMC work is not always to attenuate signals. It also means ensuring that desired signals arrive to their intended destination.

PETER STENUMGAARD info@justmedia.se

Handheld process calibrators offer high accuracy and stability Three models with specialised functions for loop diagnosis and thermocouple or RTD simulation Yokogawa has introduced the CA300 Series of handheld process calibrators: a family of three models featuring high accuracy and stability, with each model incorporating a dedicated range of functions for loop diagnosis, thermocouple simulation and RTD (resistance temperature detector) simulation, respectively. The new models, which supersede the company’s existing CA11E voltage/current calibrator and CA12E temperature calibrator, are designed to aid the periodic inspection and calibration of field measurement and control devices in plant maintenance operations. The accuracy and stability of the new calibrators reflects today’s increasing emphasis on the stable and safe operation of plants, where process calibrators are required to be more efficient while offering higher quality. At the same time, the control devices themselves are getting more precise, so that the process calibrator has to be more accurate. The three new models in the CA300 series are the CA310 volt/mA calibrator for loop diagnosis, the CA320 thermocouple calibrator and the CA330 RTD calibrator. The CA310 is a dedicated process calibrator which is designed to perform transmitter control-loop checks and inspection of the associated devices by providing a 20 mA simulated sink function and by supplying 24 V loop power while simultaneously measuring the output signal precisely. With an accuracy of ±0.015% of reading on both source and measured current and voltage, it is three times more accurate than the earlier CA11E model. A 250 ohm resistance is embedded for HART or BRAIN communication. The CA320 is a dedicated process calibrator designed for the inspection and calibration of thermocouples and temperature controllers, and again offers a threefold enhancement with a typical accuracy of ±0.5oC for a Type K thermocouple. It is compatible with JIS and IEC standard thermocouples, and also meets the ASTM and GOST-R standards for the inspection and calibration of 16 types of industry standard thermocouples. The CA330 is a dedicated process calibrator for carrying out inspection and calibration of RTDs. It has double the accuracy of the existing CA12E with a basic accuracy of ±0.3oC, which puts it in the top class of handheld devices for sourcing resistance output and measuring the output of sensors. It is compatible with JIS, IEC and GOST-R standard thermocouples, and meets the standards and regulations for the inspection and calibration of the 14 types of standard RTD. Each unit measures 90 x 192 x 42 mm and weighs 440 g. A wide range of accessories including power adaptors and a carrying case is available.

Source: Yokogawa


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Waveguide Mixers Boast Impressive Conversion Loss Performance in Rugged Compact Packages from Pasternack


Pasternack adds new millimeter wave (mm-wave) waveguide frequency mixers available in six down-conversion and six up-conversion models that cover full Ka, Q, U, V, E, and W bands. Designs utilize high performance GaAs Schottky Barrier Beam Lead Diodes in balanced configurations that require a +13 dBm LO drive and display low levels of conversion loss.

Paper submission deadline is: Dec. 21, 2015

The 2016 Asia Pacific International Symposium on Electromagnetic Compatibility & Signal Integrity (APEMC 2016) will be held from May 18 to 21, 2016 in Shenzhen, China. The 2016 APEMC so far have a very warm response, received 3 Topical-Symposiums, namely Smart Grid and Power Electronics EMC; Integrated Circuit EMC and Wireless Power Transfer Technologies. In addition, also received over 20 workshops, tutorials and special/focused sessions as well as industrial forums. The 2016APEMC conference also features the emerging fields such as 5G Communications, Multiphyics modeling, EMC in information security.

Pasternack’s new waveguide mixers, also referred to as waveguide converters, are a key building block component of mm-wave receivers used to down-convert very high frequency signals to usable RF frequencies for cost effective signal processing. They are also very useful for test and measurement applications to convert signals to frequency levels that can be measured with available equipment. Similarly, these mixers can be used to efficiently up-convert RF signals to millimeter wave frequencies for point-to-point radio and millimeter wave radar applications. The new waveguide frequency mixers from Pasternack operate over RF and LO frequency bands ranging from 26.5 to 110 GHz with an IF frequency covering DC to 18 GHz. Depending on the model, conversion loss ranges from 6 to 9 dB typical with 20 dB typical RF to LO isolation. Maximum RF input power is +5 dBm and performance is specified over an operating temperature of 0°C to +50°C. Rugged gold plated package designs are thermally stable for high reliability and feature compact dimensions with integrated waveguide sizes ranging from WR-28 to WR-10. – Pasternack’s new waveguide frequency mixers are desirable for a variety of signal conversion applications including radar, communication systems and test instrumentation,” explains Tim Galla, Active Components Product Manager at Pasternack. “Our comprehensive in-stock selections of up and down converter waveguide mixers deliver low conversion loss levels across full Ka, Q, U, V, E, W bands.

For more information: www.apemc.org

Källa: Pasternack

EMC solutions for innovation Need EMC support in your work? We are a company with expertise in EMC and perform EMC testing in our laboratory in Mölndal, Sweden and also work with consulting and education in EMC. Our consultants can e.g. lead the EMC work within large complex projects, or review a layout in a few hours to give proposals for action for better EMC performance. Contact Tony Soukka, +46-734-180 981 or tony@emcservices.se to discuss your project.

info@emcservices.se | www.emcservices.se


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See emission and immunity sources at components level! Using the EMC-Scanner during the early stages of design enables you to detect potential emission or immunity problems before they become integrated into the product and expensive to correct. See what an EMC scanner can do for you, visit our website www.detectus.com.

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Real-time link between Optenni Lab software and Copper Mountain Technologies USB VNAs creates efficient simulation solution for antenna designers Optenni Ltd has released a new version of its matching circuit optimization software Optenni Lab™, supporting a link to Copper Mountain Technologies (CMT) USB VNAs. The link enables users to stream the measured data directly into Optenni Lab, where the user can specify the matching targets and synthesize matching circuits essentially in real time. Using this connection, users can easily test antennas and virtual matching circuit prototypes in different impedance environments. – We are excited to have Optenni Ltd as a solutions partner, said Alex Goloschokin, managing director of Copper Mountain Technologies. – The interface between CMT VNAs and Optenni Lab creates a seamless link between measurements and simulations. Antenna designers will be able to monitor the antenna performance under various measured operating conditions and environments as seen through synthesized matching circuits.

GenesysTM 3U 15kW Programmable Power Supply Series Adds High Current 30, 40 and 50V Models

Optenni Ltd. recently demonstrated this software solution at European Microwave Week in Paris with Copper Mountain Technologies.

TDK Corporation announces the introduction of three new models to TDKLambda’s Genesys™ series of programmable DC power supplies. The series is now available with outputs of 30V at 500A, 40V at 375A and 50V at 300A and output powers of 15kW. These higher current units address the requirements for applications in the OEM, Industrial, Aerospace and ATE markets including: Semiconductor and Automotive Test, Component Test/Burn-in and Magnet supplies. Carrying a 5-year warranty, the TDK-Lambda Genesys™ high current models have the same features and compact dimensions (3U high and 19” (483mm) wide) as the existing 60V to 600V 15kW models. The units can operate in either constant current or constant voltage mode and accept three-phase 400VAC or 480VAC inputs, with passive Power Factor Correction. Higher power systems can be configured using the Master/Slave “Advanced” Parallel operating mode. This mode configures the Master unit to be the single point for programming, measurement and status of the total current of the paralleled system. Thus, four units can operate as a single 60kW power supply, increasing the flexibility for system designers.

Källa: MTT Design and Verification

Source: TDK

– The measurements from the Copper Mountain Technologies USB VNA are directly available for matching circuit optimization in the Optenni Lab software. This connection creates an efficient workflow as users are seeing the total performance of the real prototype antenna and simulated matching network in real time, said Dr. Jussi Rahola, CEO of Optenni Ltd.

Do you need to verify your product? We can help you with all kind of environmental durability testing SP has capacity to handle all kinds of environmental durability testing, such as • Mechanical tests (vibration, shock, free fall etc.) • Climatic tests (thermal shock, temperature cycling, humidity) • Chemical tests (salt mist, gas corrosion, chemical load, artificial sunlight) Our accreditation list covers all relevant standards. Almost all sizes of test object can be handled, from small to very large. Access to the market? SP can perform accreditation tests and issue certificates for products such as equipment for use in fire detection and fire alarm systems installed in buildings. Contact Mats Lindgren, SP Technical Research Institute of Sweden, +46 10 516 5447, mats.lindgren@sp.se Kennet Palm, SP Denmark, +45 26 14 75 43, kennet.palm@sp.se SP Technical Research Institute of Swedens vision is to be a leading international innovation partner. We create value and contribute to the sustainable development of industry and society as a whole by investing our expertise and resources throughout the innovation process.

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Joint IEEE International Symposium on Electromagnetic Compatibility and EMC Europe, Dresden 2015

EMC 2015 August 16-22 2015 in Dresden, Germany. The symposium was a joint event between two of the leading international EMC symposia, IEEE EMC and EMC Europe. The venue of the symposium was the International Congress Center Dresden.


he Congress Center is located along the Elbe River only a few minutes by foot from the historical city center of Dresden. This year, more than 400 submissions were received from industry leaders, recognized professionals, and academia worldwide across a variety of topics and disciplines within EMC. About 290 of these submissions were accepted for publication. The total number of attendees was about 1000 including exhibitors. Keynote speaker was Prof. Dr. Siegfried Fiebig, CEO of Volkswagen Sachsen GmbH. The welcome reception was located at the Volkswagen Transparent Factory which is an automobile production plant in Dresden. The name is a word


play on the double meaning of transparent and glassy, referring to both optical transparency and transparency of the production process. The main purpose of the factory is the assembly of Volkswagen’s luxury sedan, the Phaeton. The technical sessions of the symposium covered a large variety of topics: Circuits and Devices, Shielding, Low Frequency EMC, EMC for Emerging Wireless Technologies, Smart Grid EMC, EMC Management, EMC in Communication Systems, EM environment, System EMC Prediction, Filters and Conducted Coupling, Reverberation Testing, Emission Measurements, Advanced Models and Time Domain Methods, Modelling Applications, including Reverberation Chambers, Signal and Power Integrity, Hybrid and Electrical Vehicles, Electrical Powertrain, Electrical Power Supply, Analysis Automotive Systems, Field - Wire Coupling and Radiation, Immunity Measurements, Antennas, Measurement Analysis, Modelling Applications and Uncertainty Analysis in Simulations, Practical Applications of Numerical Modelling, Signal and Power Integrity, Nanotechnology and Advanced Materials in EMC. Except for the technical sessions, special sessions and workshop sessions were also conducted in a wide area of topics. As usual, EMC in automotive applications as well as different aspects of reverberation chambers gained lots of interest. Besides from traditional areas of EMC, some younger areas were also represented. An example of such growing topic is the area of Electromagnetic Information Security and Countermea-

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sures. The global interest in information security can be seen in lots of technology areas and also within the area of EMC. As in EMC Europe 2014 in Brügge, a special session was performed on this theme even in Dresden. Here, different aspects on information security related to electromagnetic properties were covered. Examples of such presentations were: Security Simulation against Side-Channel Attack on Advanced Encryption Standard Circuit Based on Equivalent Circuit Model K. Iokibe1, T. Watanabe2, and Y. Toyota1, (1) Okayama University, Okayama, Japan, (2) Industrial Technology Center of Okayama Prefecture, Okayama, Japan

covered the interference risks between military and civilian wireless services, see Figure 2. Another paper covered the topic of how well impulsive interference can be approximated as Additive White Gaussian Noise for performance estimation on direct-sequence spread spectrum communications, see Figure 3. Peter Stenumgaard info@justmedia.se  

Method for Estimating Fault Injection Time on Cryptographic Devices from EM Leakage K. Nakamura, Y. Hayashi, N. Homma, T. Mizuki, and T. Aoki, Tohoku University, Sendai, Japan Electromagnetic Circuit Fingerprints for Hardware Trojan Detection J. Balasch, B. Gierlichs, and I. Verbauwhede, KU Leuven, ESAT/COSIC, Leuven, Belgium It is likely to assume that this theme will continue to grow in future EMC conferences. Another area that grows since a few years back is EMC issues related to wireless technologies. In Dresden, the track “EMC for Emerging Wireless Technologies” had a strong Swedish representation with six out of ten papers. Two of these papers covered the interference vulnerability of the mobile technology LTE (Long Term Evolution). One paper

Figure 1. Keynote speaker Prof. Dr. Siegfried Fiebig, CEO of Volkswagen Sachsen GmbH.

Figure 2. Dr Kia Wiklundh from the Swedish Defence Research Agency (FOI) presents the paper entitled “The Risk of Coexistence Problems Between DAB and DVB-T2 and Military Services at the 225-240 MHz Band”.

Figure 3. Sara Örn Tengstrand from the Swedish Defence Research Agency (FOI) presents the paper entitled “Performance Estimation of DSSS Wireless Systems in Impulsive Interference”.

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Modern equipment and front edge competence = correct data values. www.janlinders.com, +46 31-744 38 80, info@janlinders.com

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A Vision That Requires Strategic Choices

The number of mobile subscriptions in the world is now as large as the number of people. To ensure future market growth, the mobile industry is working towards a vision that will make today´s use of mobile communications look like a mere starter. INTRODUCTION By the use of a massive technology step in wireless communications, the successor to 3G and 4G mobile technology—5G—will open the way for the Networked Society, in which wireless technology will be used to connect equipment within all sectors of society. Sweden is one of the leaders in the development of 5G and this shift in paradigm may unleash tremendous opportunities for economic growth. At the same time, several highly important strategic choices will have to be made, both by the responsible authorities and business actors, to deal with society’s increased vulnerability and citizens’ privacy issues. This massive increase in wireless systems will increase the vulnerability to attacks using electromagnetic interference and cyberattacks, since such attacks can be performed at a distance from a wireless system. In recent years, researchers have demonstrated some of the possibilities; several examples are highlighted in more detail below.

Figure 1: The increased amount of data traffic through mobile networks grows much faster than the revenues from mobile subscriptions, creating a “revenue gap.”

DRIVING FORCES BEHIND THE VISION Every ten years or so, technology steps occur in mobile communications. Once a decade, a new generation of mobile network technology comes along: the first mobile networks (1G) appeared in the 1980s, GSM (2G) followed in the 1990s, 3G arrived at the turn of the century, and LTE (Long Term Evolution) began rolling out in 2010, and has evolved to 4G. Sweden has always been one of the leading countries in the industrial development of all these generations, and remains so now. This time, however, the ambition level is dramatically higher and a tremendous technology step is planned. The main cause of the mobile industry’s high ambition level for 5G is to be found in economic considerations. Mobile data usage is rapidly increasing in both handheld devices and laptops. It is estimated that global mobile data traffic will grow by more than 200 times from 2010 to 2020, and by nearly 20,000 times from 2010 to 2030. Therefore, new investments and upgrades are necessary to meet and keep up with the demand for higher data transfer rates in mobile broadband networks. The operators are facing a number of challenges related to the scalability and cost structure of cellular systems, all of which must be resolved


if ever higher data rates are to be ensured. At the same time, the use of flat-rate subscriptions (a fixed price per month for mobile broadband) limits revenues, since the user cost for a mobile subscription has been reduced or remained constant in recent years. This has created a situation known as the ”revenue gap,” shown schematically in Figure 1.  A new concept of cost-efficient scalable infrastructure for the growing amount of mobile data must be found. Furthermore, since the number of mobile subscriptions that are possible in the world is finite, given the limited number of people, new applications for mobile broadband communications are necessary to ensure further market growth. The answer is to equip most electronic devices with wireless Internet access. By doing this within most sectors of society, we will create the Networked Society. 5G is expected to be the first network designed to be scalable, versatile, and energy-smart for a hyper-connected “Internet of everything.” The idea of connecting devices that are not handled by persons is not new in itself. The potential “Internet of Things” (IoT) has been discus-

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sed for several years. However, such connections to the Internet are still very much isolated initiatives, and IoT applications are typically developed as specialized solutions. The consequence is limited connectivity between the products offered by different vendors or for different domains, e.g. for transport, energy, or “smart cities.” The 5G vision can be seen as the necessary technical enabler to really make IoT happen at full scale. 5G is being designed as the key enabler of the future digital world, where ubiquitous ultra-high broadband infrastructure will support the transformation of processes in all economic sectors and meet the growing consumer market demand. The wireless part of global Internet traffic is expected to grow from approximately 50% today, to about 75% in 2020, and the first 5G products are expected to be available in 2020. As Sweden is one of the top leaders in telecommunications, we have always been early adopters of new telecommunication services in Figure 2: In the vision of the Networked Society, wireless connections will be used in most areas. different social applications. This means that Sweden will be one of the first countries to experience the new challenges that this massive adoption of wireless technology will create for Wireless systems can be attacked in several ways, for example by jamsociety. It is the kind of situation that presents both opportunities and ming, with the aim of disrupting transmission and thus creating a Dechallenges. By making the right choices, Sweden may be able to take nial of Service (DoS); eavesdropping, for acquiring critical information advantage of the former rather than struggle with the latter. from the transmission; and spoofing, to enable manipulation of the system with false information. It is crucial to reflect on these threats in THE 5G VISION advance, so that society-critical services will not be dependent on wireThe vision of the Networked Society involves, in principle, all sectors of less solutions that are easily vulnerable to attack. Criminal actors are society, as seen in Figure 2. Examples of 5G applications are ubiquitous: already exploiting that vulnerability: Swedish and international media smart cities, e-health, smart homes, smart grids, smart agriculture, inregularly report, for instance, how jamming is being used in connection telligent transport systems (ITS), logistics, industrial control, environwith theft and burglary. mental monitoring, education, entertainment and media. The potential is considered so far-reaching that some actors are already saying that a An example of how an everyday device equipped with wireless acnew gold rush is being spurred by the opportunities of the Networked cess can increase vulnerability to cyberattack was provided by former Society. The technical goals for 5G are so ambitious that today’s perforUS Vice President Dick Cheney, when he was interviewed on CBS’s mance will be massively exceeded. Examples are a 10-100 times higher 60 Minutes programme, on 20 October 2013. Mr Cheney said that user data rate, 1000 times more mobile data per area (per user), 10he was so concerned that terrorists might hack the medical device 100 times more connected devices, and 10 times longer battery life for implanted near his heart that he had disabled its wireless access. The low-power massive machine communications, where machines such as computer security expert, Barnaby Jack, later demonstrated, at the sensors or pagers will have a battery life of a decade. It is expected that BreakPoint Security Conference in Melbourne, how he could remothese requirements will be fulfilled at a similar level of cost and energy tely and suddenly cause a pacemaker to deliver an 830 volt shock. In dissipation per area as in today’s cellular systems. Thus, the 5G vision 2015, two security researchers, Charlie Miller and Chris Valasek, deis not just a traditional step in evolution from previous generation momonstrated that they could hijack a vehicle over the Internet, without bile systems; it is a true shift of paradigm. In the Networked Society, any dealership-installed device to facilitate access. By hacking into the flow of information between devices will be dramatically increased. a 2014 Jeep Cherokee, the researchers were able to turn the steering wheel, briefly disable the brakes and shut down the engine. Later, Fiat Yet with new technology steps, there are always new challenges to Chrysler Automobiles issued a voluntary safety recall to update the grapple with, and technical availability alone is not the sole criteria software in about 1.4 million U.S. vehicles. for bringing a specific technology into use. In the present case, the vulnerability of both the societal and individual privacy aspects need Another example is the demonstration, by security researchers, Runa to be handled in an appropriate way. This immediately raises several Sandvik and Michael Auger, of how a remotely-controlled smart rifle questions about security and privacy and calls for important strategic from TrackingPoint could be hacked from a distance. Their technique choices to be made. can wreak havoc with the gun’s targeting computer, causing it to miss its target or prevent the rifle from firing. In a real situation, such intervention VULNERABILITIES THAT DEMAND STRATEGIC CHOICES would mean that the operator would have lost control over the weapon. Wireless technology itself creates new vulnerability compared with wired connections. Deliberate attacks on wireless systems require no acAlthough the above are only a few examples of what is already possible cess to the direct physical location of the system, but can be performed today, they indicate how a rapid and massive increase of wireless Interat a distance. Thus, cyberattacks that until now have only been possible net access is creating a completely new and evolving complex of secuwhen carried out within wired networks can be performed at a conrity threats. The European Cybercrime Centre, EC3 (Europol), foresees venient physical distance from the wireless systems. Since all wireless more targeted attacks on existing and emerging infrastructures. These devices are designed to receive limited signal levels in the air, they can include new forms of data theft, blackmailing and extortion schemes, be blocked simply by transmitting a stronger signal in the appropriate such as ransomware. Ransomware is a type of malware that allows its frequency band. Standard civilian wireless technology is in general not creator to infect a system (e.g., a smart car, or smart home) and restrict robust against such interference signals, and better protection against access to it until a ransom is paid. Not only financial harm, but even them is in general expensive.

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physical injury and possibly even death are among the potential outcomes of such penetration. Trust will be, and needs to be, the basic foundation of the Networked Society and it must be underpinned by security and privacy. If not, the vulnerability of critical services will rapidly increase, at the same time as the industry will be unable to exploit the full business potential. Just one of many important strategic choices is the need to decide: in the Networked Society, what society-critical functions should be connected to the Internet in the first place? Allowing surveillance systems, first-responder systems, border-control systems, energy systems, air traffic control or water systems to become part of the Networked Society will open up for increased vulnerability to deliberate attacks. An important strategic decision would be to choose selected parts of critical infrastructure for complete exclusion from being connected to the Internet at all. A similar issue concerns which society-critical functions should be wirelessly connected to the Internet, since, as explained above, this makes possible both hacker intrusions and jamming attacks at a distance from the system. Here, one choice could be to allow wireless access to critical systems only within a controlled physical area, where only authorized personnel have access. The vision for the Networked Society is to make our everyday lives easier and boost the efficiency and productivity of businesses and their employees. The data collected will help us make smarter decisions. But this will also have an impact on privacy expectations. If data collected by connected devices is compromised, it will undermine trust. Data about energy consumption in a house, the technical status of various household appliances, and so on, may be used not only by business actors, but by criminals who might want to check whether the house is empty. And how do we handle the ethical aspects of how to use data from health monitoring, sent from a wireless bracelet? It must be made clear to the average consumer how the use of data is regulated with respect to privacy and ethical concerns. Without such clarity, it might be difficult to make the average consumer an enthusiastic user of all services in the Networked Society. This applies especially to Europe, where previous research in IoT projects indicates that concern about privacy is very important. Since Sweden is one of the leading countries working with this vision, it is reasonable to assume that this shift of paradigm will reach our society at an early stage. Again, this may provide us with a greater opportunity not only to protect our own society from threats, but to strengthen and profit from our lead in the know-how and technology that goes with being a world leader in the field. The Internet is still not secure, so we cannot expect the Networked Society to be secure either. However, security is constantly evolving to meet new challenges, and awareness of Internet security is strong


among the responsible authorities in Sweden. A recent example is the report, Information Security—Trends 2015, a Swedish Perspective (report MSB851), jointly produced by The Swedish Armed Forces, the National Defence Radio Establishment, the Swedish Civil Contingencies Agency (MSB) and the Swedish National Bureau of Investigation. The report addresses seven trend areas and gives an overall picture of the situation in the information security field, as it stands now; the coming massive increase of wireless systems in the Networked Society, however, will further increase its complexity and the vulnerability. Therefore we are bound to meet ever newer challenges, both regarding Internet security and electromagnetic interference, as discussed above. To maximize the opportunities and minimize the vulnerabilities of the Networked Society, it is more important than ever that thoughtful strategic choices are made long in advance, since the complexity of the coming technology step might not leave room for ad hoc solutions afterwards. Questions about the extent to which society-critical services should be part of the Networked Society, and how the massive amounts of information available in these networks should be handled, must be decided in advance, if we want to avoid creating a highly vulnerable society with low trust from its users. The vision of the Networked Society offers the largest opportunities, in civilizational terms, but also the most complex challenges with respect to security and privacy, of any previous technology step taken by our society. Peter Stenumgaard info@justmedia.se

Peter Stenumgaard has a PhD in radio communications. He is a Research Director and works as Head of the Department of Information Security & IT Architecture at FOI. He has worked as adjunct professor, both at Linköping University and the University of Gävle. He has long experience of research in both military and civilian applications and has also been the director of the graduate school, Forum Securitatis (funded by Vinnova), within Security and Crisis Management. He worked for several years on the JAS fighter aircraft project, on the protection of aircraft systems against electromagnetic interference, lightning, nuclear weapon-generated electromagnetic pulse (EMP) and HPM (highpower microwaves).



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Electronic Environment 4.2015 Eng

New Flexible/Twistable Waveguides from Pasternack

Pasternack, expands their waveguide product portfolio with the addition of new flexible waveguides that operate up to 40 GHz over nine frequency bands. This offering consists of 36 unique models of flexible waveguide twists ranging in size from WR-137 (as low as 5.85 GHz) to WR-28 (up to 40 GHz). Pasternack’s flexible/twistable waveguides, also referred to as a “flexguide”, utilize helically wound silver coated brass strips surrounded by a flexible and twistable, yet durable, neoprene sleeve. The ends of the waveguide are terminated with brass flanges available in nine waveguide sizes and multiple flange styles. Typical VSWR for these flexible waveguides ranges from 1.05:1 up to 1.35:1 depending on waveguide size and frequency. Insertion loss performance is similar with typical levels as low as 0.07 dB. These waveguides will flex in both the E and H planes and can also twist. Flanges in lower frequency versions are available in both UG and CPR styles. The new flexible waveguides sections from Pasternack act as a malleable conduit in waveguide systems where there is not perfect alignment for a traditional rigid waveguide section. Often an ideal solution for test labs or prototyping, these flexible waveguides can easily be flexed and twisted to conform to various misalignments in waveguide systems. These flexible waveguide twists can be ordered in standard lengths including 12, 24 and 36 inches with same-day shipping. – Our new family of flexible waveguide components provides designers and engineers an in-stock source of flexible/twistable waveguide solutions for their applications up to 40 GHz, explains Mark Blackwood, Passive Components Product Manager at Pasternack. – Pasternack’s rapidly expanding ready-to-ship waveguide family is the largest in the industry and provides customers a comprehensive suite of waveguide solutions.

Source: Pasternack

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Cold Dry heat Change of temperature Damp heat cyclic Composite temp./humidity cyclic test Damp heat, steady state

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Electronic Environment 4.2015 Eng

DO WE REALLY NEED THE EMC REQUIREMENTS? Robotic lawn movers, small autonomous robots, are becoming more and more popular in the gardens. With a minimum effort the garden is kept tidy, without the noise and emissions from a petrol engine. But how about EMC-related emissions then? And will the lawn mower co-exist with other products?


www.electronic.nu – Electronic Environment online

Electronic Environment 4.2015 Eng

Elsäkerhetsverket, the Swedish National electrical safety board, is the authority taking care of the EMC directive in Sweden. This is done by market surveillance and inspections of installations and products in use. As the market for those lawn mowers expand, reports of EMC related problems start reaching us. In some crowded neighbourhoods lawn movers sometimes don’t get on with the neighbours ‘mower. Radio interference and problems with ADSL internet access has been reported. Those reports have raised the interests of the authorities to do some market surveillance, this is usual practice. HOW THEY WORK These electrical lawn mowers are indeed quite sophisticated. They work (at least are they supposed to) within their own garden and when the batteries are getting exhausted they return to the charge station for some new energy. The charge station also produce a signal which is fed to a wire along the garden boundary. The lawn mower is searching for that signal and moves around in a random way within this area. The wanted signal is of low frequency, some tenths of a kilohertz, and with a proper design there is no reason for EMC-related problems. The lawn mower itself is quite small and has no cables attached when operating so it shouldn’t be causing any trouble. The power supply seems to be of switch mode type, the usual EMC precautions apply but that’s nothing special today where almost all power supplies are switched. PRE-TESTS Four lawn mowers were bought and pre-tested at our premises. It soon became obvious that the boundary wire and its signals were the root cause of the EMC problems, at least for some of them with particularly one bad example. Signals were examined with a current probe and the signals looked very different, some models having a rather high level of radio frequency signals. This is most likely completely unnecessary and a sign of poor filtering at the signal output. The worst model was tested in a real garden with a shortwave dipole antenna nearby. It was not surprising to see that a high level of RF signals at the boundary wire resulted in a high signal level in a receiver connected to the antenna.  GOING FURTHER Our pre-tests convinced us to perform full emissions tests on all lawn mowers purchased. This was performed by an EMC test lab. It was doubtful if the so called essential requirements in the EMC directive were fulfilled. The test report confirmed our suspicions, the result exceeded levels given in harmonised EMC standards. Most likely the product will be banned from the market, something which can also be motivated by our field test.

Initial test

Comparison, on (yellow) and off (white trace) measured with a shortwave antenna

IN THE REAL WORLD As most residential areas are rather crowded it is very likely that high emissions levels like this can cause serious problems. Risk of radio interference is obvious, radio amateurs using short wave communications will probably suffer badly from the lawn mower showed here. Signals from the boundary wire can induce interference in telephone cables, the cause for the ADSL problems mentioned in the beginning. CONCLUSION This is a typical example of the need for the authorities to follow market trends and evaluate the products. It is always beneficial ta act proactive in order to avoid unnecessary problems. In most cases EMC problems can be avoided simply by proper design and awareness of their electromagnetic environments. Following classic EMC measures, like zoning, filtering and shielding, compliance with the EMC directive protection requirements can be achieved. Finally, the EMC requirements are of course needed, together with market surveillance. Henrik Olsson, Elinspektör Elsäkerhetsverket

In the garden

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EMC-TEST EQUIPMENT radifield DARE Instruments har utvecklat ett helt nytt koncept för att skapa homogent fält vid immunitetsmätningar Koppla bara till Er egna signalgenerator. Område 1GHz upp till 6GHz , 10V/m vid 3 metersträcka. fair-rite material 75 Fair-Rite material 75 är ett helt nytt ferritmaterial speciellt framtaget för att dämpa i det lägre frekvensområdet mellan 200kHz till 5MHz





MäTNINg av EMf/ElECTroMagNETIC fIEldS SafETy aNd hEalTh EffECTS Modell SMP2 är ett portabelt instrument för EMF mätningar. Med 6 probar(isotropiska) täcker den området 1 Hz-18GHz EMF mätning enl. Direktiv 2013/35/EU Prob WP400, 1Hz-400kHz är isotropisk för RMS mätningar av E-fält: 1V/m-100kV/m och H-fält: 500nT-40mT. För mätning av fält kring kraftledningar och stationer, tåg, industri mm. Levereras med akrediterad kalibrering enligt ISO17025



INfraTEK Effektanalysator 108a Effektanalysator för 1-, 2-, 3-, 4-, 5- eller 6 faser. Spänning från 0,3 – 1500 V (peak), ström 1,5mA till 40A. Onogrannhet 0,02% avläst värde + 0,02% område. Touch-screen TFT display. 1G Byte minne. Bandbredd DC till 2MHz. Kommuniktion: Ethernet, RS-232, UBS eller GPIB. radiPower rPr3006W Effektmäthuvud Speciellt utvecklat för trådlösa nätverk. Mätområde 10MHz–6GHz.

darE rPr2006P Effektmäthuvud 6 ghz Puls/Burst Effektmäthuvud för mätning på puler och burstsignaler. Frekvensområde från 9 kHz till 6 GHz. Mätområde från ´55 till +10 dBm. dMaS (dutch Microwave absorber Solutions) EMC Hybrid Polystyren Absorbent EHPA-612-T45. En Europeiskt tillverkad absorbent av polystyren med frekvensområde 30 MHz–40 GHz, även anpassad för att monteras med ferritplattor för de lägre frekvensområdena. Konerna monteras asymmetrisk för att bättre efterlikna verkligheten. DMAS är självklart både REACH och ROHS godkänd. INSTrUMENT för UThyrNINg Ett alternativ till att köpa kan vara att hyra. Kanske behöver du ett viss instrument under en kortare tid ex under tiden er egen utrustning är på kalibrering. Vår hyreslösning är ett kostnadseffektivt sätt att få de test- och mätinstrument som du behöver, utan den höga investeringskostnaden för köp och intstrumentunderhåll. CE-BIT har en mångd olika instrument som vi nu har möjlighet att kunna hyra ut. För mer information besök vår hemsida cebit.se

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