Electromagnetic Pulse Protection Research Articles

High Power Electromagnetic Pulse Damage Effect of a Low Noise Amplifier

Low noise amplifier (LNA) is the most sensitive component in the front end of a wireless communication system, which is very vulnerable to coupling attack of high-power electromagnetic pulse (HPEMP). This paper first analyzes the damage mechanism of a high-power electromagnetic pulse to a low noise amplifier, then designs the damage experiment of high-power electromagnetic pulse injection to the low noise amplifier, and verifies the damage mechanism and damage threshold of a certain radar low noise amplifier. The experimental results show that the LNA is not affected by the linear effect of high-power electromagnetic pulse. When the high-power electromagnetic pulse exceeds the damage threshold, thermal melting occurs between the FET grid sources in the device, causing permanent damage to the LNA and performance failure. This conclusion can provide data support for the high-power electromagnetic pulse protection design of this type of LNA.

An Intelligent Method Based on Time–Frequency Analysis and Deep Learning Semantic Segmentation for Investigating the Electromagnetic Pulse Features of Engine Digital Controllers

A novel intelligent extraction method based on time–frequency analysis and deep learning semantic segmentation were proposed for detailing electromagnetic pulse (EMP) sensitive frequency bands of engine digital controllers. In this method, wavelet transformation was performed to convert EMP-coupled signals into image data sets. Two semantic segmentation networks, namely fully convolutional networks and DeepLabV3+, were used to train and verify the obtained image data sets. The performance of the two models was compared using the confusion matrix and Kappa coefficient. Threshold segmentation, binarization, and average pooling operations were sequentially performed on the feature map output of the networks, and EMP characteristic pixel percentage was calculated using the time–frequency map. The original image was segmented by using the result of the binarization of the feature map output by the last layer of the network as a mask. This technique is immune to the interference caused by noise pixels when calculating the spectrum index. The proposed method has improved the EMP feature extraction accuracy of the model, and the overall performance of the DeepLabV3+ network model is proper. It was performed to obtain a theoretical basis for subsequent targeted EMP protection.

The protection design method of the engine control system under electromagnetic pulses.

This study assessed the survivability of an engine control system under intense electromagnetic pulses. It investigated the electromagnetic sensitivity of the system under the action of intense electromagnetic pulses. In this work, the evaluation focuses on the terminal circuit of the control system. It proposes a co-design method for electromagnetic pulse protection circuits on a printed circuit board. The electromagnetic interference mechanism and phenomena were analyzed through simulation and experiments. The electromagnetic susceptibility of the control system was tested using the bulk current injection test method, and the pulse coupling signal of the sensitive part was obtained. Subsequently, the terminal circuit was analyzed using a numerical calculation method. The pulse coupling signal was injected into the terminal circuit. Thus, we can determine why the control system exhibits sensitive phenomena. Then, a protection circuit of the terminal circuit was established. The design method's advantage is accurately locating the circuit's sensitive points and reducing the controller circuit's electromagnetic sensitivity by designing the circuit without drastically changing the original circuit. At the same time, the redundancy of protection circuit design can be effectively reduced.

Optically Transparent Ultrawideband Electromagnetic Stealth Metasurface for Microwave Absorption and Scattering

For the issue of stealth and electromagnetic protection of weapons and equipment in strong electromagnetic pulse (EMP) environment, a transparent double-sided ultrawideband metasurface is proposed to realize wave absorption/absorption-scattering integrated function in two directions. The interactions between backscattered waves produced by the meta-atoms are manipulated and optimized simultaneously by hybrid far-field scattering pattern analysis and genetic algorithm to achieve ultra wideband destructive interference. Both simulation and experimental results demonstrate that the polarization-independent −10 dB radar cross section (RCS) reduction performance can be achieved for more than 128% of the fractional bandwidth (4–18.25 GHz) at forward incidence, and the absorption more than 90% in the range of 2.75–12.75 GHz (fractional bandwidth more than 129%) at backward incidence. The scattering and absorbing characteristics of the metasurface are still well maintained in the range of 0°–50° oblique incidence. The method of this letter has an important prospect in related applications of strong EMP stealth and protection technology under the integration of information equipment in the future.

Experimental Study on the Coupling Mechanism of Sensors under a Strong Electromagnetic Pulse.

This paper presents a study on the electromagnetic effects of a main fuel control system under the action of a strong electromagnetic pulse. It assesses the electromagnetic sensitivity of a speed sensor and a linear variable differential transformer (LVDT) sensor. This assessment focuses on the control system’s electromagnetic effects and the sensors’ coupling signals. The effects and signals were determined using radiation and pulse current injection tests. Analysis of the signal at the system power port shows that it is the same as those for the two test methods. Based on analysis of the working mechanism and terminal signals of the sensors, the electromagnetic sensitivity of the system is different under the different electromagnetic pulse conditions. The electromagnetic sensitivity characteristics of the sensors were verified, and the electromagnetic effects of the main fuel regulation control system were analyzed. Meanwhile, the degree of sensor coupling mechanism caused by the electromagnetic coupling effects of the main fuel regulation control system under strong electromagnetic pulses were studied. These findings have clear practical implications for electromagnetic pulse protection of aero-engine control systems.

Experimental Study on Electromagnetic Shielding Characteristics of a Fe-Based Amorphous Soft Magnetic Composite

An Fe-based amorphous soft magnetic composite with flexibility and elasticity was fabricated to shield harmful electromagnetic waves in industrial and military defense applications. Through the combination and structural arrangement of the amorphous soft magnetic sheet and the conductive sheet, the inlet (POE) form of electromagnetic waves was artificially diversified, and shielding performance was measured according to the criteria of MIL-STD-188-125-1 in the range from 1 kHz to 10 GHz, in consideration of the electromagnetic pulse (EMP) protection. As a result, the shielding effectiveness of 80 dB was achieved in a triple “sandwiched” structure by alternately stacking an iron-based amorphous soft magnetic material on top of a flexible conductive sheet at a 90-degree angle, rather than in parallel.

A Hybrid 2-D–3-D Miniaturized Multiorder Wide Bandpass FSS

In this letter, a hybrid multiorder wide bandpass frequency selective surface (FSS) with high selectivity and low insertion loss is achieved by combining the two-dimensional (2-D) FSS structure and the 3-D vertical structure. The 3-D periodic vertical printed circuit board pieces (PVPCB) are used as the dielectric layer in the unit cell to achieve a proper band flatness without introducing great insertion loss. The multiorder response of the proposed FSS is achieved using a series of 3-D PVPCB instead of stacking the 2-D FSS layers. The proposed FSS unit cell is constructed by combining the full-wave and equivalent circuit simulations, since the physical structures have a good one-to-one correspondence with the circuit elements. The module design method is used to accelerate the design procedure, and the simulation result proves the effectiveness of this design method. Finally, the prototype is fabricated and measured to prove the effectiveness of the proposed FSS. The measured relative bandwidth and rectangle coefficient achieved is 130.4% and 0.76, respectively. The measured maximum insertion loss over the whole passband is 0.7 dB. Because of its strong capability of out-of-band rejection, the proposed FSS structure is a good candidate to enhance high-frequency electromagnetic pulse protection of wideband radar systems.

Non-nuclear Electromagnetic Pulse Threat of Critical Infrastructures and Protection Strategies

Major infrastructures are vital for the modernization and operation of a country and the safety of major infrastructures is crucial for national security. In recent years, the generation technology of non-nuclear electromagnetic pulse (EMP) sources has gradually matured and develops to be universal and concealed. Therefore, the non-nuclear EMP has become a realistic threat for major infrastructures. Ensuring the electromagnetic safety of major infrastructures is an urgent strategic task for China. This study takes the non-nuclear EMP threat of major infrastructures as the research object, clarifies the basic concepts of and major demands for EMP protection for major infrastructures, and analyzes the measures taken by developed countries in this field from the aspects of national policies, industrial standards, fundamental research, and emergency management. In addition, the key technologies for efficient non-nuclear EMP protection are discussed, focusing on forward design, equivalent test and evaluation, and threat monitoring and prediction. Moreover, this study analyzes the current status and existing problems regarding non-nuclear EMP protection of major infrastructures in China and proposes several fundamental strategies including strengthening government leadership, promoting scientific research, formulating standards and guidance, stimulating the vitality of enterprises, conducting classified and staged implementation, boosting talent cultivation, and promoting public training. This study can provide a basic reference for the non-nuclear EMP protection of major infrastructures and further support China to handle new threats.

Simulation and Experimental Study of the Field Distribution of Engine for Electromagnetic Pulse

The protection of electromagnetic pulse (EMP) is important for aircraft due to vulnerable electronic equipments are installed. The control box of engine is also suffering from EMP and seldom studied. Meanwhile, most of work related to EMP protection focus on shielding design. Few works consider the effect of engine shell. The field distribution induced by EMP and its influences on the controller layout are unaddressed. This work will comprehensively investigate the field distribution characteristics of an engine under EMP, which is studied by simulating and experimenting methods. The transmission line matrix (TLM) is used to simulated field distribution of the bounded wave simulator and aero-engine, which provides better placement for equipment under test in the simulator. The field differences of bounded wave simulator and plane wave have been analyzed by using CST software. The feasibility of plane excitation instead of bounded wave simulator model excitation is checked, which has been verified by using the engine model. Then, the distribution characteristics of transverse and longitudinal fields surrounding the aero-engine are obtained, and the surface current distribution of the engine is also obtained in the simulation. The aero-engine simulation is excited by bounded wave simulator under CST software. According to the corresponding monitoring points, the simulated field distribution characteristics are verified by using the largely bounded wave simulator. Finally, the influence of field distribution on the layout of the engine electronic control system is analyzed, which provides a reference for the anti-electromagnetic pulse design of the engine electromagnetic controller.

Introduction to the method of estimating time-domain response based on amplitude-frequency characteristics

How to use the amplitude-frequency characteristics to reconstruct the signal to obtain the time-domain response has always been a concern in the field of nuclear electromagnetic protection. So far, in practical applications, parametric modeling and non-parametric modeling have been used to solve related problems. This article summarizes the research and development of using amplitude-frequency characteristics to recover time-domain signals in the field of nuclear electromagnetic pulse protection, and briefly introduces the shortcomings of the two methods in combination with specific experiments.

Large Transformer Criticality, Threats, and Opportunities

Large power transformers (LPTs) represent a critical “tent‐pole” in national electric power grid, and national resiliency. They are essential to both the generation and transmission sectors of our electric power grid. They are known to be targets in adversaries' plans to debilitate our critical infrastructures. Their high cost and supply chain issues involving months to years of replacement times dictate the importance of survivability assurance. Transformer vulnerability and protection are addressed for physical attacks, cyber, and electromagnetic effects, including solar weather geomagnetic disturbance (GMD) and high altitude burst nuclear electromagnetic pulse (EMP) effects. Programs have been underway to improve transformer and transformer substation cyber and physical resiliency. Similar programs are lagging for electromagnetic threats. Transformer vulnerability to EMP remains a subject of conjecture since no large power transformer has undergone threat‐level EMP testing. Prevalent claims that LPTs are immune to EMP are premature.The Savannah River National Laboratory has developed a test program and designed a test bed to complete testing on LPTs including physical set‐up, injection sources, and measurement equipment to enable transformer testing under real load conditions without harming the larger power grid. The SNRL test bed will enable tests to determine both transformer vulnerability thresholds and the effectiveness of protection devices. A concerted national effort is needed to determine LPT vulnerabilities and to expeditiously develop and certify effective EMP and GMD protection approaches.

Development of Decision-Making Factors to Determine EMP Protection Level: A Case Study of a Brigade-Level EMP Protection Facility

This study developed decision-making factors to classify electromagnetic pulse (EMP) protection levels and determine various protection measures. We proposed three EMP protection levels of 80, 60, and 40 dB by considering the characteristics of military equipment and factors that determine EMP protection level, based on a Delphi study. We modeled EMP protection facilities for brigade-level troops to evaluate the derived decision-making factors and applicability of differential protection levels. The natural attenuation effect of soil was confirmed for structures installed underground. The shielding effect of wet soil was up to 30 dB. Considering the 20 dB EMP resistance of military equipment and the 30 dB of attenuation of wet soil, new materials with 30 dB of shielding efficiency could be used to meet an EMP protection level of 80 dB. Therefore, we confirmed that EMP protection measures could be established to build mobile, lightweight shelters. If lightweight shelters are constructed by applying the differential protection level scheme, they can be applied as a more effective EMP protection measure. Furthermore, differential protection measures can be adopted as a sustainable defense facility policy approach, wherein lightweight protection facilities replace conventional heavyweight facilities.

An Electromagnetic Protection Design Evaluation Algorithm for Complex Electronic Systems Based on Margin Estimation

Based on the analysis of random error sources in the design margin evaluation of electromagnetic protection for complex electronic, it is researched on a method of evaluating electromagnetic pulse protection capability, the total error standard deviation evaluation theory is analysed. A new method for evaluating the electromagnetic pulse protection capability of complex electronic systems based on the lower limit estimation of design margin and corresponding reliability and confidence is proposed. So taking the evaluation of electromagnetic protection design interval of a certain type of electronic information system as an example, the application and the qualification conditions of the algorithm are illustrated.

Analysis of coupling characteristics of coaxial line parallel to lightning current channel

Base on the analysis of the coaxial coupling theory, the experimental model of the coaxial cable short-range coupling lightning electromagnetic pulse is established to study the problem of coaxial cable short-range coupling lightning electromagnetic pulse on the ship mast and high tower. The combination wave generator is used to simulate the 8/20 μs lightning current waveform, and the metal bar with the length of 1 m and diameter of 0.016 m is used to simulate the lightning channel as the radiation source. The length of the coaxial cable and the distance from the radiation source are changed for the test. The conclusion is as follows: when the coaxial cable is coupled with lightning wave in a short distance, the voltage waveform of cable terminal is still double exponential wave, with strong damping oscillation at 0.1 ∼0.4 μs. When the cable terminal is open circuit or connected with matching resistance, the rising time is shorter, about 1 μs; when the cable terminal shielding layer is grounded, the rising time is longer, about 10 μs. The peak voltage and energy coupled to the coaxial cable at short distance are positively correlated with the cable length, and inversely correlated with the distance from the radiation source. The energy that the cable is coupled to mainly comes from the low-frequency part, and there are multiple energy peaks below 100 Hz. Using fitting curve and experimental data, when the coaxial cable terminal is open circuit, the lightning current reaches 30 kA, the cable length is 30 m, and the distance from the lightning channel is 0.15 m, the peak value of the voltage coupled to the cable terminal is 66 V. It has certain guiding significance and value in the practical application of electromagnetic pulse protection.

도체 판의 자기장 차폐효과 분석: 확산과 슬롯 효과

This study analyzes the low-frequency magnetic shielding effectiveness (SE) of a metal plate, in terms of diffusion and slot effects, by conducting a numerical simulation and implementing an analytical solution. When the metal has a low conductivity, the SE is dominated by the diffusion effect. However, when the conductivity and frequency both increase, the slot has a major influence on the SE. These results can be used as guidelines in the shielding design and SE requirements of electromagnetic pulse protection facilities.

A novel high-altitude electromagnetic pulse (HEMP) protection circuit for RF applications

A High-Altitude Electromagnetic Pulse (HEMP) protection circuit with ultra-low loading capacitance for RF applications that does not degrade RF circuit performances is proposed. Principle of operation, loading capacitance, leakage current, EMP clamping characteristics and robustness over transient over-voltage pulse will be presented. As a case study, a 5.8 GHz WLAN InGaP/GaAs hetero-junction bipolar transistor (HBT) power amplifier with this compact EMP protection circuit is demonstrated. The test result shows that the EMP protection circuit can provide 18 kV contact discharge per IEC 61000−4−2 standard without degradation in PA performances.

Electromagnetic pulse protection of piezoelectric vibration acceleration sensor

Piezoelectric vibration acceleration sensor is widely used in our life. If there is a big electromagnetic pulse in the environment, the electromagnetic pulse will be coupled into the circuits through power cords and data cords. The electromagnetic pulse protection circuits of power cords and data cords are researched in this paper. The piezoresistor and transient suppression tube are used as transient components in the protection circuits. Through simulating, the optimized protection circuit is found. The method of group comparison is proposed in this paper. The simulation and experimental results show that the protection circuits proposed in this paper can protect the sensor very well.

Effects of high-altitude electromagnetic pulse on overhead pipeline

High-altitude electromagnetic pulse may cause damage to electronic equipments through coupling pipeline system. In order to study the effects of high-altitude electromagnetic pulse on overhead pipeline, the electromagnetic field-to-overhead pipeline coupling equations are derived from Maxwell’s equ ations. The coupling equations are solved in frequency domain by applying the Green’s functions, and the time-domain waveforms of induced currents and voltages are obtained by using inverse Fourier transform. The currents and voltages at both ends and in the middle of pipeline are calculated by MATLAB software. It is shown that the peak values of the currents along the pipeline don’t vary much. The voltages at the ends of the pipeline are larger and the voltage polarity at one end is opposite to another, while the voltages in the middle of the pipeline are smaller. The effects of system characteristics on induced voltages are presented, such as the length of the pipeline, the height of the pipeline, the radius of outer surface of the pipeline and the conductivity of the ground. The results of these studies are applicable to electromagnetic pulse protection.

美军有关核电磁脉冲研究的指令、指示、标准及试验操作规程

核环境中武器装备的生存能力研究是美军的一项重要工作，抗核电磁脉冲防护是其中一项重要内容。美军很早就在这一领域开展了相关研究，并取得了丰富的成果。为了指导相关工作开展，美军颁布了较为系统的指导性、技术性文件。本文主要介绍了美军有关核电磁脉冲的指令性文件、环境与效应要求、加固/防护标准、试验标准、电磁脉冲环境下武器系统生存能力试验操作规程。 Research on arms and equipment survivability in nuclear environment is an important work of the U.S. military, and nuclear electromagnetic pulse protection is a main part of this work. The U.S. military started studying these problems since many years ago, and made a great progress. In order to guide this research, the U.S. military issued series of documents about electromagnetic pulse, just like DoD Directives, DoD Instructions, environment & effects requirements, hardening/protect standard, test standard, arms and equipment survivability test operations procedure in nuclear electromagnetic pulse environment. They are all introduced in this article.

The Lightning Electromagnetic Pulse Coupling Effect Inside the Shielding Enclosure With Penetrating Wire

AbstractTo study the lightning electromagnetic pulse (LEMP) coupling and protection problems of shielding enclosure with penetrating wire, we adopt the model with proper size which is close to the practical engineering and the two-step finite-difference time-domain (FDTD) method is used for calculation in this paper. It is shown that the coupling voltage on the circuit lead inside the enclosure increases about 34 dB, when add 1.0 m long penetrating wire at the aperture, comparing with the case without penetrating wire. Meanwhile, the waveform, has the same wave outline as the lightning current source, shows that the penetrating wire brings a large number of low frequency component into the enclosure. The coupling effect in the enclosure will reduce greatly when penetrating wire has electrical connection with the enclosure at the aperture and the coupling voltage increase only about 12 dB than the case without penetrating wire. Moreover, the results show that though the waveguide pipe can reduce the coupling effect brought by the penetrating wire, the exposing part of penetrating wire can increase the coupling when the penetrating wire outside the enclosure is longer than the waveguide pipe and the longer the exposing part is, the stronger the coupling is.