High Power Electromagnetic Research Articles

Investigating Electromagnetic Interference Induced Risks for Autonomous Driving

Abstract. The results of immunity tests on components of self-driving automobiles to radiated high power electromagnetic (HPEM) pulses are presented in this work. It is of particular interest to investigate such automobiles' resilience towards deliberate attacks with electromagnetic interference (EMI). Different types of HPEM capabilities at the Bundeswehr Research Institute for Protective Technologies and CBRN Protection (WIS) in Munster are applied for this investigation. Two types of automotive components have been tested, a two-axis acceleration sensor and an electronic power steering unit. Statistics of errors from the devices under test (DUTs), as well as a characterization of the applied pulses are presented. A correlation can be drawn between the pulse repetition rate or the amplitude of the applied pulses and the severity of the effect on the DUTs.

Power-modulated reconfigurable nonlinear plasmonic devices without DC power supply and feed circuit

High-power electromagnetic (EM) waves can directly modulate the parameters of nonlinear varactor diodes through the rectification and Kerr effects without relying on external sources. Based on this principle, we propose a power-modulated reconfigurable nonlinear device based on spoof surface plasmon polariton (SSPP) waveguide loaded by varactor diodes, without applying DC power supply or feed circuit. Increasing the input power level reduces the effective capacitance of the varactor diode, leading to a blueshift in the cutoff frequency of the SSPP waveguide. This feature can be employed to realize the switching on/off of the input signal depending on the signal power. On the other hand, the transmission state of a low-power signal can be controlled by inputting another independent high-power EM wave simultaneously. Increasing the power of the control wave will enable the low-power signal within a wider bandwidth switched from off to on states. Experimental results are presented to show the excellent performance of the power-modulated reconfigurable SSPP device. This method can reduce the system complexity and provide inspiration for reconfigurable all-passive multifunctional devices and systems.

Predicting the coupling of HPEM waveform with a power amplifier in perforated conductive enclosure using FDDM/VF

AbstractOne of the most common methods to protect electronic and telecommunication systems in a high‐power electromagnetic (HPEM) environment is using a conductive enclosure. Amplifiers are the vital parts in transmitter and receiver systems as the main components of a telecommunication system, so investigating the effects of HPEM waveform on their performance is very important. The Presence of apertures in the body of the conductive enclosure, as well as non‐linear elements such as transistors in amplifiers, adds to the complexity of examining the coupling of electromagnetic fields on the performance of amplifiers. Considering the importance of the topic, in this study, the impact of the HPEM waveform on the power amplifier inside the conductive enclosure has been investigated. By using the finite difference delay modelling (FDDM) numerical method as a stable method followed by the vector fitting (VF) method, the electromagnetic problem has become a circuit problem, which allows examining the response of the power amplifier and any circuit, including non‐linear elements against the interference field. Responses of bipolar linear and non‐linear components in the perforated conductive enclosure by the proposed method have been compared with the results obtained by computer simulation technology microwave studio (CST‐MWS) for verification.

Body Feature Intercomparison of Specific Absorption Rate Induced by High-Power, Portable, and Broadband Electromagnetic Sources [Bioelectromagnetics

Body Feature Intercomparison of Specific Absorption Rate Induced by High-Power, Portable, and Broadband Electromagnetic Sources [Bioelectromagnetics

Transverse electric-thermal-fluid instabilities in an electromagnetic heat exchanger

Electromagnetic (EM) heat exchangers (HX) are critical components in power beaming applications where EM waves are radiated towards an EM HX, which then converts incident energy into heat or mechanical work. An EM HX consists of a lossy ceramic and a fluid flow that maintains thermal contact with and transfers heat from the ceramic. These materials have loss factors which increase with temperature, so that beyond a critical temperature thermal runaway can take place. Stable characteristic temperatures, which depend on the rate of energy removal from the system, during high-power EM heating of ceramic materials suggest that coolants would be in the gaseous phase. As a first step, we consider a model EM HX system consisting of a horizontal channel containing a viscous, dielectric fluid with a constant coefficient of thermal expansion, bounded from below by a grounded ceramic receiver of finite thickness. The system is subject to plane EM waves, propagating normally to the channel from above, and polarized in the same direction as a plane Poiseuille flow of the coolant. With the Boussinesq approximation, we calculate the base state solution of the system and then investigate the linear stability of this base-state. We find three modes of instability: thermal runaway, Rayleigh-Bénard convection, and a novel instability which we call the fringe-field instability, that takes place in the plane normal to base-state flow direction.

Determination of Shielding Effectiveness of a Subnanosecond High-Power EM Interference by an Enclosure with Aperture Using Time Domain Approach

Determination of Shielding Effectiveness of a Subnanosecond High-Power EM Interference by an Enclosure with Aperture Using Time Domain Approach

Development of the EM Field in a Shielding Enclosure with Aperture after Interference Caused by a Subnanosecond High-Power Parallelly Polarized EM Plane Wave Pulse

Due to the increase in the threat of attacks with high-power electromagnetic (EM) pulses, there is great interest in metallic enclosures with high shielding effectiveness (SE). Necessary technological apertures in these enclosures reduce their effectiveness. Understanding the penetration and internal propagation of the high-power EM pulses into an apertured enclosure is fundamental to assessing the EM SE of the enclosure. In the present paper, results of the numerical simulations of development of the EM field in a shielding enclosure with aperture after the interference of a subnanosecond high-power EM plane wave pulse of the parallel polarization (having the duration of 0.3558 ns and the amplitudes of the electric and magnetic fields of 106 V/m and 2.6 × 103 A/m, respectively) are presented. The results obtained include 3D and 2D images , vector maps of the EM field developed inside the enclosure, and time-varying distributions of the electric charges formed on the inner walls of the enclosure. They revealed the mechanism of formation of the EM field inside the enclosure caused by the subnanosecond high-power parallelly polarized EM pulse. The EM field formed in the enclosure with aperture has the form of the electric and magnetic field interference structures. They are a superposition of the incident EM pulse field, which entered the enclosure through the aperture in the way described by the geometrical (ray) optics, the electric field generated by the electric charges formed on the aperture edges and inner sides of the walls of the enclosure, and the magnetic field generated by the surface current formed on the aperture edges and on the inner walls of the enclosure. The amplitudes of the electric and magnetic fields of the strongest EM interference structures decrease non-monotonically to about 0.7 × 105 V/m and 200 A/m at t = 5 ns. We found that the points in the enclosure are subjected to the disturbance of a long series of subnanosecond EM pulses, which we have called internal EM pulses. The amplitudes of these internal pulses are lower than those of the incident EM pulse. Nevertheless, they can pose a severe EM hazard inside the enclosure due to their large number (about 900 internal pulses in 30 ns). This means a fundamental change in the character of the EM disturbance caused by the subnanosecond pulse when the enclosure with aperture is used as a shield.

Development of an Equivalent Circuit Model for the Design of Array of Electrically Small Antennas

In this article, we present a fully parameterized circuit model of an array antenna that relates antenna performance and field coupling to the physical parameters of the elements as represented through a circuit model. We demonstrate that the simplified model can be used as a surrogate for full-wave modeling during the initial optimization steps in array design. The model accounts for mutual coupling between array elements both through the feeding network and through free space. We present a method to calculate the mutual coupling between elements in the array antenna that is parameterized in terms of the size and location of the individual elements, and these circuit models provide excellent agreement with the scattering parameters calculated by the full-wave numerical model. The model is applied to the analysis of a specific built array configuration, and we demonstrate that the simplified circuit model can have strong predictive effects for designing arrays of electrically small antennas (ESAs) and predicting their ultimate performance by comparing with numerical and limited experimental measurements. The study is motivated by high power electromagnetic (HPEM) applications, where arrays of densely space elements can help reduce the antenna size necessary to radiate extremely large power signals.

Infinitesimal Dipole Modeling From Sparse Far-Field Patterns for Predicting Electromagnetic Characteristics of Unknown Antennas

The identification of unknown antennas and analysis of electromagnetic wave vulnerability are important for effective attacks and/or protection in high-power electromagnetics (HPEM). Using electromagnetic clues, antenna modeling becomes possible, and its electromagnetic properties can be analyzed by predicting area-wide radiation patterns. To model an antenna, an infinitesimal dipole modeling (IDM) technique, utilizing clues from sparse far-field patterns, was used in the present study. The IDM approach obtained the equivalent infinitesimal dipole (ID) for the antenna configuration current using Green’s function. The sparse far-field pattern was determined for a movement trajectory, using air reconnaissance. Random far-field data acquisition paths were considered cumulatively in the 1–10 range in this case. The approach also used external exposure information about the antenna, such as the operating frequency and size. For simulations and measurements, a ridged-horn antenna operating at 2.4 GHz was used. The overall radiation pattern reconstructed using the IDM approach was correlated at 0.78 when one path was considered in the simulations. As the considered paths were accumulated, the correlation tended to increase, with the correlation for ten paths exceeding 0.98. The estimated radiation pattern characteristics of antennas can be utilized for communication reception characteristics and/or electromagnetic wave vulnerability analysis.

Risk Analysis of HPEM Threats for Linear RF Channel with Pyramid Horn Antenna Based on System-Level SPICE Modeling

High power electromagnetics (HPEMs) pose a potential threatening risk to the wireless communication system, especially according to the main coupling path of the RF front-end channel. SPICE modeling of the responses coupled on the RF channel is crucial for the EM risk assessment, which helps us learn more about how the pulse conducts on the RF channel. A simplified linear RF channel with pyramid horn antenna is taken as an example by the selection of the key electronic modules of the actual wireless system. This paper proposes a system-level SPICE circuit model for the simplified RF channel according to the hybrid methods of the antenna electromagnetic simulation and SPICE modeling of the RF circuit. The equivalent circuits of the horn antenna illuminated by HPEMs are established with the Vector Fitting method based on Thevenin and Norton theorems. The short current response as the excitation files for the SPICE models are obtained by the commercial electromagnetic simulation of the horn antenna illuminated by Multiple HPEM environments. Equivalent circuits of a micro-strip bandpass filter are also derived with π type circuit structure based on the measured admittance data. Then we analyze the HPEM risk faced by the RF channel by considering multiple HPEM environments. The norm theory is utilized to analyze the waveform characteristics from electric fields of HPEMs to the responses of the RF channel. The ratios of the responses versus electric field for each norm are computed and the EM risk degree is ranked based on those results. The results demonstrate that high power microwave is the highest threatening risk for the linear RF channel compared to the other two HPEMs such as ultra-wide band, high altitude electromagnetic pulse. Finally, the flowchart of EM risk assessment is presented based on a previous analysis, which will benefit the EMC design in engineering.

Electromagnetic-Thermal Analysis of FTU under the High-Power Electromagnetic Environment

The feeder terminal unit (FTU) is a critical component of any electric power system that works in a complex electromagnetic environment. However, innovative research of theoretical analysis of electromagnetic–thermal practices inside the FTU system is missing in the literature. This work presents the theoretical methodologies for calculating and analyzing the electromagnetic–thermal influence of FTUs in a high-power electromagnetic (HPEM) environment. The numerical outcomes reveal that the surface of the FTU and connecting cables under powerful electromagnetic pulses (EMP) induce significant electromagnetic fields and high temperatures. Significantly, the electromagnetic pulse and injection of heat through the wires into the FTU may cause interference and possibly damage to the FTU’s circuits and electronics. This work serves as a reference for electromagnetic compatibility (EMC) design of FTUs and provides numerical analysis for ensuring the normal operation of FTU devices under harsh electromagnetic environments.

Detection Circuits for System-Level Signal and Power Noises Due to High-Power Electromagnetic Pulses

Four types of circuits for detecting system-level noises due to high-power electromagnetic (HPEM) pulses have been proposed and implemented in compact modules. The detection circuit provides digital information about the level or polarity of noises generated at specific power or signal nets. The sensed data are directly saved in the hardware, which is free from malfunctions of the applied system. For characterization and evaluation of the proposed circuits, transmission line pulse (TLP) and damped sinusoidal (DS) sources were constructed. The operation threshold curves of each detection circuit were theoretically derived and validated by measurements using the TLP source. The proposed detection circuits were then applied to the radiated HPEM experiments with the DS source. From the operation data of the detectors, the system-level noises generated by the radiated HPEM waves were quantitatively analyzed based on the operation threshold curve of each detector. The proposed detection circuits can play a role of a noninvasive diagnosis method for evaluating the effects of HPEM pulses inside a target application system.

Numerical Evaluation of Human Body Near Field Exposure to a Vehicular Antenna for Military Applications.

BackgroundThe use of electromagnetic (EM) technologies for military applications is gaining increasing interest to satisfy different operational needs, such as improving battlefield communications or jamming counterpart's signals. This is achieved by the use of high-power EM waves in several frequency bands (e.g., HF, VHF, and UHF). When considering military vehicles, several antennas are present in close proximity to the crew personnel, which are thus potentially exposed to high EM fields.MethodsA typical exposure scenario was reproduced numerically to evaluate the EM exposure of the human body in the presence of an HF vehicular antenna (2–30 MHz). The antenna was modeled as a monopole connected to a 3D polygonal structure representing the vehicle. Both the EM field levels in the absence and in the presence of the human body and also the specific absorption rate (SAR) values were calculated. The presence of the operator, partially standing outside the vehicle, was simulated with the virtual human body model Duke (Virtual Population, V.3). Several exposure scenarios were considered. The presence of a protective helmet was modeled as well.ResultsIn the area usually occupied by the personnel, E-field intensity radiated by the antenna can reach values above the limits settled by international safety guidelines. Nevertheless, local SAR values induced inside the human body reached a maximum value of 14 mW/kg, leading to whole-body averaged and 10-g averaged SAR values well below the corresponding limits.ConclusionA complex and realistic near-field exposure scenario of the crew of a military vehicle was simulated. The obtained E-field values radiated in the free space by a HF vehicular antenna may reach values above the safety guidelines reference levels. Such values are not necessarily meaningful for the exposed subject. Indeed, SAR and E-field values induced inside the body remain well below safety limits.

Improved FDTD Method for Coupling Analysis of a Dielectric-Coated Wire Above Rough Soil Surface Under HPEM Pulse

An improved finite difference time domain (FDTD) method is proposed to calculate the transient coupling of a dielectric-coated wire above the rough soil surface under the high power electromagnetic (HPEM) pulse. The improved method is based on the domain decomposition technique, in which the dielectric-coated wire and the rough surface are allocated into the target subdomain and the rough surface subdomain, respectively. The reflected waveform from the rough surface is computed by applying the FDTD method combined with the time-domain Huygen's technique. The incident field on the target subdomain is calculated through the superposition of the excitation fields generated with the directly incident wave and the reflected wave from the rough surface. The near-field distribution and the energy-flux density (EFD) inside the dielectric-coated wire are simulated by running the FDTD in the target subdomain. The accuracy and high efficiency of the improved method are validated and demonstrated by comparing with the conventional FDTD method. Finally, the influences of some parameters related to the rough soil surface and dielectric-coated wire on the EFD are analyzed through the typical examples.

EMC Personality Profile

With this Personality Profile, I would like to introduce you to Dr. Chaouki Kasmi. Dr. Kasmi is the Chief Researcher at the Directed Energy Research Center at the Technology Innovation Institute (TII), a cutting-edge United Arab Emirates (UAE) based scientific research center. I first met Chaouki Kasmi during a one week course (HPE 201–2011) on High Power Electromagnetics (HPEM) which took place in September 2011 at “Schloss Noer” in Germany. I was a faculty team member and Chaouki was a young Ph.D. student who attended the course. As he was eager for knowledge and due to his personality, Chaouki Kasmi was noticed by the entire faculty team. Since September 2011, Chaouki and I have met frequently at the AmerEM/EuroEM conferences.

EMC Personality Profile

With this Personality Profile, I would like to introduce you to Nicolas Mora, one of our current EMC Society Distinguished Lecturers. The first time I remember meeting him personally and listening to his presentation was in Toulouse, France at the EUROEM 2012 conference. As both of us were working and interested in high-power electromagnetics, we subsequently met at several locations and events around the world. Currently Nicolas Mora is the Director of the EM Effects Division of the Directed Energy Research Centre of the Technology Innovation Institute (DERC-TII) in Abu Dhabi, United Arab Emirates. He was born in Bogota, Colombia and started his professional life in engineering by studying Electronics Engineering at the National University of Colombia. Nicolas received a degree in Electronics Engineering in 2007 and an M.Sc. degree (Hons.) in Electrical Engineering with a major in High Voltage Engineering in 2009, both from the National University of Colombia.

High Power Electromagnetic Waves Exposure of Healthy and Tumor Bearing Mice: Assessment of Effects on Mice Growth, Behavior, Tumor Growth, and Vessel Permeabilization.

High power radiofrequencies may transiently or permanently disrupt the functioning of electronic devices, but their effect on living systems remains unknown. With the aim to evaluate the safety and biological effects of narrow-band and wide-band high-power electromagnetic (HPEM) waves, we studied their effects upon exposure of healthy and tumor-bearing mice. In field experiments, the exposure to 1.5 GHz narrow-band electromagnetic fields with the incident amplitude peak value level in the range of 40 kV/m and 150 MHz wide-band electric fields with the amplitude peak value in the range of 200 kV/m, did not alter healthy and tumor-bearing animals’ growth, nor it had any impact on cutaneous murine tumors’ growth. While we did not observe any noticeable behavioral changes in mice during the exposure to narrow-band signals when wide-band HPEM signals were applied, mice could behave in a similar way as they respond to loud noise signals: namely, if a mouse was exploring the cage prior to signal application, it returned to companion mates when wide-band HPEM signals were applied. Moreover, the effect of wide-band signals was assessed on normal blood vessels permeability in real-time in dorsal-chamber-bearing mice exposed in a pilot study using wide-band signal applicators. Our pilot study conducted within the applicator and performed at the laboratory scale suggests that the exposure to wide-band signals with the amplitude of 47.5 kV/m does not result in increased vessel permeability.

Design of Compact Solid-State Modulator for High-Power Electromagnetic Pulse Generation

The proposed compact solid-state modulator for the generation of high-power electromagnetic (HPEM) pulses uses a lithium polymer battery as the input power source and is capable of achieving a 100-Hz pulse discharge rate with a peak voltage of 400 kV for 2 min. The developed pulse generator consists of two charging units. The primary charging unit is designed to work with 200-A battery current, which increases switching losses and temperature increments at the main switch. To compensate the problems, a half-bridge three-phase structure is connected to transformers via the proposed delta-star connection that decreases the turns ratio of the three-phase transformer effectively. Furthermore, the resonant components are intentionally placed on the secondary side of the three-phase transformer, which is characterized by low current and high voltage conditions. The secondary charging unit uses the resonance between the two capacitors, and the inductor must protect not only the controller, which is susceptible to HPEM pulse effects, but also the output rectifying diodes of the primary charging unit from the peak 20-kA pulse discharging effect. The design procedures and analysis are verified with simulations for each charging unit. The experimental results using various loads, including the actual tesla transformer, validate the system performance and confirm a 94% power efficiency with a peak power density of 431 W/L.

William A. Radasky: Elected as a Member of the National Academy of Engineering

In February 2021, Dr. William A. Radasky was elected to the National Academy of Engineering (NAE) in recognition of his distinguished contributions to engineering, “For leadership in the development and application of electromagnetic transient disturbance and protection standards for national security and commercial systems.” Dr. Radasky is President and Managing Engineer of Metatech Corporation, an IEEE Life Fellow and a Lord Kelvin Award Winner. He received the Richard R. Stoddart Award in 2018 from the IEEE EMC Society “For fundamental contributions to the understanding of high power electromagnetic (HPEM) and intentional electromagnetic interference (IEMI).” Congratulations to Dr. Radasky from the IEEE EMC Society!

Maximizing Radiated High-Power Electromagnetic Threat to Transmission Line System Under the Constraints of Bounded Bandwidth and Amplitude

This article aims at identifying the worst-case waveform of a radiated high-power electromagnetic (HPEM) for maximizing threats to the victim electric system. In contrast to the previous analysis where constraint on energy-density of the HPEM field is imposed, the proposed analysis considers an upper bound constraint for the amplitude of the electrical waveform, which appears to be a more concerned restriction for practical radiation system. In this connection, evolutionary algorithms, i.e., genetic algorithm, stud-genetic algorithm (StudGA), and particle swarm optimization, are resorted to for solving the problem. In particular, it is found that StudGA outperforms the other two approaches for solving the proposed problem. The results demonstrate an optimized wideband HPEM is only marginally more threatening to the victim system than an attentively tuned continuous-wave/narrowband interference, and it is a fairly good compromise to apply these fields for the worst-case immunity assessment, especially when the difficulty in generating wideband HPEM of complex waveform details is considered.