EMC Europe . International Symposium on Electromagnetic Compatibility was arranged the 2 – 6 September in Barcelona Spain. It was locally organized by Universitat Politècnica de Catalunya, Campus Nord. EMC Europe is the major European conference on Electromagnetic Compatibility and covers a wide area of topics within EMC. As usual, the conference had tutorials, workshops, poster sessions and oral sessions. High quality scientific and engineering papers were presented in a variety of themes within EMC.
The tutorials covered a wide area of EMC topics and therefore offered opportunities for attendees interested in further education within EMC. The conference had more than 700 participants and over 200 papers from 35 countries were presented. Five papers came from Sweden. Four of these papers were from the Swedish Defence Research Agency (FOI) and one was from QAMCOM Research & Technology AB.
The Automotive area has been large within EMC recent years and this was also the largest theme at EMC Europe 2019 with four oral sessions and four workshop sessions. A special theme, also related to vehicular applications, was “Challenges in Special Applications of Electrically Small, HF Vehicular Antennas”, that had four workshop sessions. HF (High Frequency) usually means the frequency region of 3 – 30 MHz. Since the wavelength for these frequencies are typically considerably larger than the dimensions of the platform, one basic challenge is to design electromagnetic efficient antennas. One advantage of this frequency region is that large communication distances can be achieved since the radio wave can be reflected in the ionosphere. HF communications can therefore cover long distances, without dependency of other infrastructure. The HF-workshop sessions covered different aspects of HF communication antennas, e.g.:
- Basic technical challenges: Emergency Communication needs in remote disaster areas, Automotive EMC, electrically short HF Antennas, critical communications SNR on short wave low bands.
- Antenna problem analysis by equivalent circuit/simulation model (car chassis, tires, short monopole, soil/ground)
- Efficiency impacting parameter studies (measured/simulated): Tire capacitance impact, Antenna Input Impedance, VSWR.
- Far Field Ant. Radiation Pattern (azimuth, elevation) impact for different soil/ground characteristic under the automobile.
Thus, at least 12 sessions covered EMC issues for automotive/vehicular applications. This shows the high interest of EMC issues in these applications. Reverberation chambers and Numerical Simulation Techniques for EMC Problems are also large areas and had three oral sessions each.
Communications had two oral sessions covering different EMC-related issues for communication systems. Communication issues are also connected to other areas e.g. antenna solutions and intentional EMI. Therefore, communication issues were also well represented at the conference. Four of the Swedish papers were related to wireless communications and are briefly summarized below. Man-made interference from solar-panel systems was analysed in the paper:
Stenumgaard and S. Linder, “Interference Impact from Solar-Panel Systems on Air Traffic Control Communications”
In recent years, solar energy systems have become more and more widely used. The interference issues connected to these systems have also started to gain interest, since both conducted and radiated electromagnetic emission can be generated by these systems. In this paper, the interference risks for Air-Traffic Control Communications were investigated. The results show that considerable interference impact, in terms of reduced communication range and increased receiver-noise level, can be caused by radiated interference from solar panels at co-location distances of 20-30 meters and below. The overall conclusion is that co-location of solar-panel systems with air traffic control communications, must be carefully analyzed not to create safety and security problems on airports.
Communication issues related to the Internet of Things (IoT) were addressed in the paper:
Wiklundh, “Understanding the IoT technology LoRa and its interference vulnerability”
Low Power Wide Area Networks (LPWAN) is the term for a wireless network that allows long range communications offering low bit rate among connected objects, such as sensors operated on a battery. The IoT technology LoRa belongs to the class of LPWAN dedicated for several new applications. LoRa is the current market leader and the expected growth of LPWAN applications is large. LoRaWAN is an open-source LPWAN infrastructure created by the LoRa Alliance and that allows other companies to create their own IoT networks based on its technology specifications. LoRa is using the unlicensed frequency band 868 MHz in Europe and 916 MHz in US. Although LoRa has been available for some years, its interference vulnerability has not been thoroughly elaborated. In this paper, the LoRa waveform with its error performance and orthogonality is clarified. It is foreseen that the unlicensed bands will experience an increased interference level that will negatively affect the communication performance.
The possibilities of using machine learning for automatic classification of interference in Air-Traffic Control Communications, were discussed in the paper:
Eliardsson and P. Stenumgaard, “Artificial Intelligence for Automatic Classification of Unintentional Electromagnetic Interference in Air Traffic Control Communications”
The rapidly increase of wireless systems in safety- and security applications calls for more automatic monitoring of electromagnetic interference in the vicinity of critical applications. For efficiency reasons, such automatic monitoring techniques need to be complemented with methods for automatic analyses and classification of the collected interference data. In this paper, the possibility of using artificial intelligence in the form of machine learning to automatically identify and classify interference signals out of the total measured electromagnetic environment, is discussed.
One paper addressed interference issues for the 5G New Radio (NR):
Fors, E. Axell, S. Linder and P. Stenumgaard, “On the Impact of CW interference on 5G NR”
Orthogonal frequency division multiplex (OFDM) is used in several modern wireless systems. OFDM has also recently been included in the standard for the fifth generation mobile system, 5G. In this work, the vulnerability of 5G NR to different types of continuous wave (CW) interference. An important conclusion of this work is that the 5G NR system is significantly more sensitive to CW interference than to white Gaussian noise. To improve the robustness against CW interference, different types of limiters on the received signal are also evaluated.
Communication issues were also addressed in the session “Intentional EMI”, that had one oral session. One of the papers was on interference vulnerability for LTE (Long Term Evolution) mobile systems:
Romero et al, “EMI LTE Physical Layer Vulnerability Test to Different Types of Jamming Signals”.
This paper presents an analysis of the susceptibility of the LTE physical layer in the presence of jamming signals. The quality of the LTE uplink is analyzed through the measurements of three parameters: Error Vector Magnitude (EVM), Occupied BandWidth (OBW) and Adjacent Channel Leakage-power Ratio (ACLR).
Other examples of papers
The fifth Swedish paper was in the area “Components, Semiconductors and IC”, and covered destructive testing of components:
Wellander, M. Elfsberg, H. Sundberg and T. Hurtig, “Destructive testing of electronic components based on absorption cross section RC measurements”
In this paper, the authors present a destructive testing procedure based on absorption cross section (ACS) measurements defined by the recorded power in a reverberation chamber (RC). Destructive testing of light-emitting diodes (LED) are performed at frequencies with maximum absorption cross section ratio (ACSR) and at frequencies with lower ACSR. The failure outcome scales with the expected maximum value distribution as a function of the number of uncorrelated samples in the RC. The required power to break the diodes at lower ACSR is consistent with the theory. The statistical distribution of the composite ACSR is modelled with a generalized beta prime distribution.
Two oral sessions were on the theme “Human Exposure & Health Protection”. One of these papers was on health issues related to wireless power transfer for electric vehicles:
Campi, S. Cruciani, F. Maradei, M. Feliziani, “Wireless Charging of Electric Vehicles: Planar Secondary Coil Position vs. Magnetic Field”
There are various wireless power transmission (WPT) applications in use, in experimental, or in implementation phase throughout the world. WPT applications are expanding to mobile and portable devices, home appliances and office equipment. The automotive industry looks at WPT for electric vehicle (EV) applications in the upcoming future. This paper provides a parametric investigation on the magnetic field produced by a WPT-system to recharge the battery of an electric vehicle, varying the position of the secondary coil in the car underbody. The considered WPT charging system operates at the frequency of 85 kHz with a power of 7.7 kW. The author´s conclusion is that this WPT-system creates a very strong magnetic field that can be critical for human exposure to electromagnetic fields (EMF) and for immunity of implanted medical devices.
Smaller, but emerging areas were also represented. One such area was “EMC in Physics Experiments and Particle Accelerators”. One paper presented an overview of EMC issues in RF stations:
C.Rivetta, “EMC issues in RF stations for particle accelerators”.
Another example of a small but emerging area was “New materials for EMC”. Two papers addressed material issues for 5G:
Alessandro Giuseppe D’Aloia et al, “Transparent Graphene-Based Absorber for Next Generation Wireless 5G Technology”
Liping Yan et al, “An Angularly Stable Frequency Selective Surface with Vent Holes for 5G Electromagnetic Shielding
Best paper awards
Best paper awards were given in the two categories “Regular paper” and “Student paper”. The winner in the category Regular was:
Kuznetsov et al, “Cyclostationary Characterization of the Interference Induced by Crosstalk Between Transmission Lines”
The winner in the category Student was:
Bendicks et al,”Simultaneous EMI Suppression of the Input and Output Terminals of a DC/DC Converter by Injecting Multiple Synthesized Cancellation Signals”
The next issue of EMC Europe is planned for 7-11 September 2020 in Rome, Italy. In 2021 EMC Europe will be a joint event with IEEE International Symposium on EMC and the venue will be Glasgow, UK. In 2022, EMC Europe will once again be organized in Gothenburg, Sweden.
Peter Stenumgaard The Swedish Defence Research Agency (FOI)