Protective properties of a missile enclosure against electromagnetic influences

In order to predict the immunity of a generic missile (GENEC), not only the electronic system but also the enclosure has to be taken into consideration. While a completely closed metallic missile enclosure shows a high electric shielding effectiveness, it is decreased substantially by apertures which could not be avoided by different reasons. The shielding effectiveness of the generic missile could be investigated by means of a hollow cylinder equipped with different apertures. Numerical simulations and measurements of this hollow cylinder will be carried out and analyzed

Analysis of the coupling of electromagnetic pulses into shielded enclosures of vulnerable systems

In order to predict the immunity to electromagnetic interference of vulnerable systems, not only the electronic system but also its enclosure has to be taken into consideration. In this work, the coupling behavior of electromagnetic pulses (EMP) and continuous wave (CW) signals into the shielded enclosure of a generic system is investigated by metrological and numerical methods. Since this enclosure forms an unwanted or parasitic cavity resonator, the enclosure`s resonance behavior as well as the characteristic quantities, i.e., the resonance frequencies and corresponding quality factors are of great interest, too. The usage of an optical field sensor reduces the influence of the measuring setup on the investigated system and thus, enables the analysis of the enclosure's resonance behavior, which delivers revealing information about the dependence of the quality factor on the aperture size of the enclosure

Measurement uncertainty caused by distance errors during in situ tests of wind turbines

During the assessment of the electromagnetic emissions of wind turbines (WTs), the aspects of measurement uncertainty must be taken into account. Therefore, this work focuses on the measurement uncertainty which arises through distance errors of the measuring positions around a WT. The measurement distance given by the corresponding standard is 30 m with respect to the WT tower. However, this determined distance will always differ e.g. due to unevenness of the surrounding ground, leading to measurement uncertainties. These uncertainties can be estimated with the knowledge of the electromagnetic field distribution. It is assumed in standard measurements, that the electromagnetic field present is a pure transversal electromagnetic field (far field). Simulations of a simplified WT model with a hub height of 100 m shows that this assumption is not effective for the whole frequency range from 150 kHz to 1 GHz. For frequencies below 3 MHz the field distribution is monotonically decreasing with the distance from the WT since it behaves like an electrical small radiator. Whereas for frequencies above 3 MHz, where the investigated model forms an electrical large radiator, the field distribution becomes more complex and the measurement uncertainty of the field strength at the observation point increases. Therefore, this work focuses on investigations where the near field becomes a far field. Based on the simulation results, a method for minimizing the uncertainty contribution caused by distance errors is presented. Therefore, advanced measurement uncertainty during in situ test of WTs can be reduced

Susceptibility of Power Line Communication (PLC) Channel to DS, AM and Jamming Intentional Electromagnetic Interferences

The use of power lines as a communication channel for transferring data between communication devices for power systems in smart grid communication systems is growing rapidly. This paper describes three different types of methods for radiating and conducting Intentional Electromagnetic Interference, IEMI, signals: Amplitude Modulated, Damped Sinusoidal and Sweep Frequency Jamming Signals. The severity of all three types of IEMI signals on a power line communication channel using a single phase of a three-phase, low-voltage power distribution board is compared. The method for measuring interference is then explained and the influence of radiated and conducted interferences on data transmission is assessed. After discussing the IEEE 1901 power line communication channel's vulnerability to IEMI, this article explains the need for a systematic risk-based approach, in coalition with the rules-based perspective, to mitigate its impact.© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Vulnerability of Wireless Smart Meter to Electromagnetic Interference Sweep Frequency Jamming Signals

The installation and use of smart home technology that uses wireless communication channels, according to the 802.11 standard series, is rapidly increasing. This article discusses the effect of Electromagnetic Interference Sweep Frequency Jamming Signal applied to a wireless smart meter installed in a three-phase domestic and light commercial electricity distribution board. More specifically, a method of frequency jamming signal generation technique, jamming signal radiation and its interference measurements method are explained in this paper. Then, the impact of disturbances are discussed and mitigation mechanisms such as construction material shielding, digital filtering and a systematic approach of electromagnetic risk assessment are given.© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Untersuchungen zur Bestimmung von hochfrequenten elektromagnetischen Emissionen von Windkraftanlagen

In diesem Beitrag wird ein Messkonzept zur vergleichbaren Bestimmung der gestrahlten elektromagnetischen Emissionen von Windkraftanlagen vorgestellt. Dazu wird anhand der normativen Lage die Notwendigkeit einer präzisierten Messvorschrift für Windkraftanlagen erläutert. Hierzu werden zunächst die Textstellen der aktuellen internationalen Norm IEC/CISPR 11 [1] bzw. der nationalen Norm DIN EN 55011 [2] aufgezeigt, die einen großen Interpretationsspielraum in Bezug auf Windkraftanlagen bieten. Anschließend werden die in der Technischen Richtlinie 9 [3] erarbeiteten Lösungen vorgestellt und analysiert. Zur Beurteilung der aktuellen normativen Lage werden sowohl Emissionsmessungen nach [2] als auch nach [3] durchgeführt, wobei bei den Messungen nach [2] bewusst die vorhandenen Interpretationsspielräume ausgenutzt werden. Die somit gewonnenen Messergebnisse zeigen, dass zum einen die in [3] beschriebene Vorgehensweise zur Reduzierung der Messunsicherheit beiträgt, zum anderen aber auch, dass weiterhin noch Aspekte mit Handlungsbedarf bestehen

Effect of Electromagnetic Interference on Integrated Circuits

Critical infrastructure may be disturbed by high power electromagnetic (HPEM) weapons. Both, short impulses and modulated/unmodulated radio frequency (RF) carrier signals may be used. The interfering electromagnetic waves may be coupled by lines between different electronic devices to the inputs or outputs of integrated circuits (ICs) [1]. By shielding the lines or the use of twisted symmetric transmission lines, this effect may be significantly reduced. On the other hand, ICs themselves are influenced by HPEM pulses. A quantitative estimate of the coupling of HPEM waves to lines on an IC itself is required to investigate the effectiveness of applicable protective measures against them

Echtzeit-Spektralanalyse zur Identifikation von Störquellen in Kraftfahrzeugen

Der Automobilsektor ist derzeit in seiner vermutlich größten Veränderungsphase seit seinem Bestehen. Die Elektrifizierung des Antriebstranges, automatisiertes bzw. autonomes Fahren und Connectivity – diese Schlüsselworte beschreiben diesen Prozess und bringen eine Vielzahl von Herausforderungen bei der Sicherstellung der EMV im Gesamtfahrzeug mit sich. Um den straffen Entwicklungszeitplan einzuhalten, sind strukturierte Vorgehensweisen bei der Fehlersuche in frühen Entwicklungsstadien notwendig. In diesem Beitrag wird anhand eines realen Beispiels gezeigt, wie mithilfe von sukzessiver messtechnischer Echtzeit-Spektralanalyse eines Einsatzleitfahrzeugs der Berufsfeuerwehr Hannover sporadische Störungen des Sprechfunks, welche nur während der Einsatzfahrt auftraten, behoben werden konnten. Hierzu wird zunächst in Kapitel 2 die Ausgangssituation vorgestellt. Anschließend wird in Kapitel 3 kurz auf klassische EMV Messungen mit einem Oszilloskop (Zeitbereich) und mit einem Spektrumanalysator (Frequenzbereich) eingegangen. In Kapitel 4 wird schließlich mithilfe von Echtzeitanalyse der Antennenfußpunktspannung, der Gleichtaktströme auf dem Bordnetz und des abgestrahlten elektrischen Felds in der Nähe des Fahrzeugs die Störquelle und der Störkoppelweg anhand von sporadisch auftretenden Störmustern identifiziert. Die Analyse dieser Störmuster führt zur schnellen Identifikation der Störquelle samt Koppelpfad und stellt den Neuheitsgehalt dieses Beitrags dar. Der in dieser Arbeit präsentierter Ansatz basiert auf den in [1] präsentierten Messergebnissen

Vulnerability of Smart Grid-enabled Protection Relays to IEMI

The electricity sector has been undergoing transformations towards the smart grid concept, which aims to improve the robustness, efficiency, and flexibility of the power system. This transition has been achieved by the introduction of smart electronic devices (SEDs) and advanced automatic control and communication systems. Despite the benefits of such modernization, safety issues have emerged with significant concern by experts and entities worldwide. One of these issues is known as Intentional Electromagnetic Interference (IEMI), where offenders employ high-power electromagnetic sources to maliciously disrupt or damage electronic devices. One of the possible gateways for IEMI attacks targeting the smart grids is the microprocessor-based protection relays. On the one hand, the malfunctioning of these devices can lead to equipment damage, including high-voltage equipment (e.g., power transformers), which represent one of the most high-cost items of energy infrastructure. On the other hand, a possible misleading triggering of these devices could cause cascading effects along the various nodes of the power system, resulting in widespread blackouts. Thus, this study presents the possible recurring effects of IEMI exposure of a typical protection relay used in smart grid substations as part of the SCADA (Supervisory Control and Data Acquisition) system. For this purpose, a test setup containing a smart grid protective unit, a monitoring box, and the device's wiring harness is exposed to radiated IEMI threats with high-power narrowband signals using a TEM waveguide and horn antennas. The effects during the test campaigns are observed by means of an IEMI-hardened camera system and a software developed to real-time monitor the device's fibre optic communication link, which is established according to the IEC 60870-5-105 protocol. The results revealed failures ranging from display deviation to various types of protection relay shutdown. Moreover, the consequences of the identified failures in a power substation are discussed to feed into a risk analysis regarding the threat of IEMI to power infrastructures

Respiration parameter determination with non-obstructive methods

Measuring respiratory parameters like the breathing frequency or the tidal volume is essential in intensive care to ensure an optimal and lung protecting ventilation. A common practice in artificial ventilation of sensitive patients like infants or neonates is the use of uncuffed endotracheal tubes in combination with continuous positive airway pressure (CPAP). This comes with the disadvantage of an unknown leakage making it difficult to detect spontaneous breathing or to measure the tidal volume reliable. A novel non-obstructive method to determine respiratory parameters as well as dynamic changes of thoracic parameters has recently been presented and uses a pair of coupled UHF (ultra high frequency) antennae. In this paper, a respective setup is investigated numerically using finite difference time domain method and experimentally using an artificial lung phantom. Both approaches show that the investigated method seems capable of allowing a contactless triggering to synchronize natural and artificial breathing. The results are compared to derive a better understanding of influencing factors and opportunities for an optimisation