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High field intensity electromagnetic radiation effect test is difficult to simulate in large-scale space, and the existing bulk current injection (BCI) technology has a limited application of the nonlinear system test. Starting from the coupling mechanism of shielded wire, an analysis model about the response of the equipment under test (EUT) is built-in radiation and injection conditions. In addition, the equivalent corresponding relationship originates between the injected excitation source voltage and the radiation field intensity. The basis for obtaining the source of the injection excitation and performing extrapolation tests is found, and the test method of BCI replacing high field intensity electromagnetic radiation is developed. Subsequently, the passing-through load and communication station tests are performed to verify the theoretical derivation and the test method. As indicated from the research results, the BCI is capable of accurately replacing the high field electromagnetic radiation effect test of the EUT, and the maximum test error reaches 2.7 dB, capable of satisfying the actual needs of the project.

In order to improve the radar’s electromagnetic protection ability, it is essential to master the law of the false alarm effect of the radar’s out-of-band third-order intermodulation electromagnetic radiation, starting from the circuit field-circuit coupling mechanism, and the mechanism of the third-order intermodulation false alarm effect is analyzed. Taking a stepped frequency ranging radar as the research object, the absolute level value of the false alarm signal is selected as the sensitive criterion of the false alarm effect. The dual-frequency electromagnetic false alarm interference effect is carried out by using the method of the differential mode injection equivalent substitution electromagnetic radiation. The results show that the dual-frequency electromagnetic interference will cause the radar to generate the third-order intermodulation false alarm signal with the random position and waveform spreading. Under a certain interference intensity, the level of the third-order intermodulation false alarm signal increases with the increase of the interference field strength. With the continuous increase of the interference field strength, the fifth-order intermodulation false alarm signal gradually appears. The imaging mechanism, the waveform characteristics, and the level change law of the fifth-order intermodulation false alarm target, are similar to the third-order intermodulation false alarm target, and its position is also random. The maximum third-order intermodulation false alarm signal can reach 18 dBmV, indicating that the radar is sensitive to the out-of-band intermodulation electromagnetic interference.

In unshielded two-wire circuits of weapon systems, the equipment at both ends of the cable needs to be tested at the same time. The theoretical model of substituting double bulk current injection (DBCI) for high-intensity radiated field (HIRF) electromagnetic radiation is established, which aims to calculate the relationship between the injection excitation voltage source and the radiation field intensity. Additionally, the conditions required for linear extrapolation is clarified. Subsequently, the test method of using DBCI for the HIRF radiated susceptibility (RS) is proposed. Next, the verification of the CST studio and the pass-through load test are performed. All results shows that the test method can avoid the influence of the impedance parameters of the two equipment at both ends, which can be applied to nonlinear terminals for the HIRF RS test.

An electromagnetic compatibility (EMC) prediction method is proposed to overcome the insufficiency of the single frequency threshold and prediction methods of statistical analysis. Two prediction models are established based on different sensitive parameters by analysis of the interference mechanism. Effect index is defined to predict EMC. If the effect index reaches or exceeds 1, the communication equipment will be disturbed. The radiation test platform of multifrequency in-band interference is designed, with two different types of communication radios as the equipment under test (EUT). The sine and amplitude modulation (AM) wave, dual-frequency, and tri-frequency radiation tests were performed. Test results show that the sensitive parameter of equipment can be distinguished by sine and AM wave susceptibility threshold; all of the effect indexes of EUT I which is sensitive to peak-field strength exceed 1 and all of the effect indexes of EUT II which is sensitive to average power are around 1. For reducing the model error, the modified Model I is proposed and the effect indexes of EUT I are about 1.1. The method in this paper can effectively solve the problem of multifrequency in-band EMC prediction for the communication equipment and improve EMC standards.

In this paper, the temperature rise method of the hot bridgewire electro-explosive device (EED) under the steady conditions is proposed. The optical fiber temperature test technique is employed. Since the measurement range of the temperature is limited for this technique, the extrapolation method is used. The relationship between the injected current (or the field strength) and the temperature rise of the bare bridgewire is analyzed and validated by experiment. The work in this paper is the basis for proposing the high-level field radiated susceptibility test methods of the systems containing hot bridgewire EED in the future.

In order to meet the actual demand of cloud lightning channel current inversion, a theoretical calculation model of lightning electromagnetic fields produced by vertical cloud lightning channel is established based on the dipole method, and the simplified relationship between the cloud lightning electromagnetic field at ground level from the vertical channel and the channel current is presented. By comparing the cloud lightning electromagnetic fields from the simplified expressions with that from the exact expressions, the influences of the observation distance, the channel length and the channel starting height on the accuracy of the simplified expressions are obtained, and the application ranges of the simplified expressions are also given.

The penetrative conductor is the most important coupling channel of bring the outside electromagnetic radiated field into the metal shielded box. In order to disclose the electromagnetic radiation coupling law of the penetrative conductor and the generation mechanism of the local electromagnetic field enhancement effect in shielded box caused by the penetrative conductor coupling, the induced current distribution law of the penetrative conductor under the condition of sine continuous wave radiation is studied in this paper. The penetrative conductor induced current distribution computation model is established under the condition of plane wave radiation. The analytic expression of the induced current distribution is derived. The penetrative conductor induced current amplitude distribution curve is plotted by using Matlab software at typical frequency point. The penetrative conductor induced current distribution law versus radiated frequency and conductor location is disclosed under the condition of plane wave radiation. The penetrative conductor induced current test platform based on vector network analyzer is developed by adopting current probe and optical fiber signal transmission system. The normalized induced current distribution curve at typical frequency point is measured. The test results verify the correctness of the penetrative conductor induced current distribution law and other theoretical analysis results.

In this paper, the test method using the directional coupling device as the injection device is employed to measure the radiated susceptibility of the antenna system. The susceptibility of the radio frequency front-end whose internal circuits are typically integrated circuits are measured. The differential-mode injection method can achieve the equivalence with both the continuous wave case and the electromagnetic pulse case.

A dual-port pulsed differential-mode current injection (DPDCI) method is proposed for high-level wide-band electromagnetic pulse (EMP) radiated susceptibility testing of interconnected systems. By employing the designed wide-band differential-mode (DM) coupling device, the susceptibility of the equipment under test (EUT) at both ends can be assessed at the same time. In order to enforce the equivalence between EMP radiation and DPDCI, the methods to obtain the waveforms of the two equivalent injection sources and their time delay difference are proposed. By using the linear extrapolation method, the results for high-level EMP radiation can be reproduced by DPDCI even if the responses of the two EUTs are non-linear. To confirm the effectiveness of the proposed method, the conversion of common-mode interference into DM disturbance on the cable inside the EUT is assessed by experiment and the impact of connecting the injection devices into the system is discussed. By using a typical interconnected system composed of a coaxial cable and typical non-linear equipment at both ends, the feasibility of the proposed method is verified.

A numerical simulation method for the fractal channel of intracloud lightning discharge is presented, and the influence of the horizontal scale of the thundercloud on the fractal dimension of the discharge channel is also analyzed. The results show that the simulated intracloud lightning discharge channel has obvious fractal structure. The larger the horizontal scale of the thundercloud, the more obvious the branch of the channel and the greater the fractal dimension of the channel.

Aiming at accelerating the simulation of the lossy reverberation chamber using the finite-difference time-domain method, a fast and accurate approach is proposed. The lumped losses of the real chamber are equivalently substituted by adding the artificial-loss atmosphere, which is evenly distributed throughout the chamber. Unlike the lumped loss, such even loss could reduce the simulation time dramatically. The conductivity of such medium is evaluated on the basis of the quality factor of the reverberation chamber, which is generally deemed as the capability of composite losses, rather than by manual attempts or experience. As examples, two different sorts of excitations are simulated to validate the correctness and generality of the artificial-loss technique.

A set of approximation expressions relating the lightning channel-base current and the lightning electric and magnetic fields on earth surface are proposed respectively in the near-zone and far-zone, by employing the transmission line (TL) model. The derived expressions show that, the electric and magnetic fields waveforms can be expressed approximately by the channel-base current waveform with different factors at a certain distances, whether in the near-zone or far-zone. The factors can be expressed in terms of the return stroke wavefront speed v, the speed of light c, and the horizontal distance r between the return-stroke channel and the observation point.

The formulas of tortuous channel lightning electromagnetic field are obtained by decomposing the current micro-source dipole and solving Maxwell's equations. The waveforms of lightning electric and magnetic fields in different areas are calculated using the transmission line model and pulse function. Then, the characteristics of lightning electromagnetic field for different channel geometries and the impact of lower section discharge channel length on electromagnetic field initial peak value are analyzed by comparing the waveforms of lightning electromagnetic fields. The results show that, the difference between the electromagnetic field waveforms of two models will decrease with the increasing of the distance and the upper section of discharge channel has little impact on electromagnetic fields in near area but the electromagnetic fields will be influenced by the upper section of discharge channel in intermediate and far field regions. Moreover, the peak value of tortuous channel lightning electromagnetic field in different field regions is mainly determined by the lower section length of the discharge channel.

On the base of analysis of probability of failure under uncertainty of susceptibility measurement in the reverberation chamber, we derive the relationship between the sample number of stirrer positions and the number of the mean value of electric field of different injected power levels during the measurement, the duration of measurement will reduce to a certain extent by select appropriate parameters. Combined on the two different approach( substitution approach and removing approach) to represent the real field strength suffered on the devices putting in the reverberation chamber based on the statistic characteristics of reverberation chamber, We propose a fast approach to perform susceptibility measurement in a stepped-mode reverberation chamber. Such an approach can be apply for a much wider range of susceptibility measurement compared with other testing environment and other approach in reverberation chamber.

A kind of electric and magnetic field generators with adjustable waveforms and intensity output to simulate lightning electromagnetic fields are presented. The electric fields measured by a dipole antenna and ranged from 0 to 300kV/m can be generated within the GTEM cell by feed-in of an impulse voltage. The magnetic fields measured by a ‘B-dot’ coil and ranged from 0 to 3000 A/m can be generated within the coil by feed-in of a surge from the lightning surge generator. The relatively homogeneous lightning electromagnetic pulse (LEMP) environment could be provided within certain area in the GTEM cell and the coil, which can be used to evaluate the immunity of small electronic systems or devices towards LEMP with low cost.

Monitoring of atmospheric electric field near ground plays a critical role in atmospheric environment detecting and lightning warning. Different environmental conditions (e.g. buildings, plants, weather, etc.) have different influences on the data's coherence in an atmospheric electric field detection network. In order to study the main influence factors of atmospheric electric field monitoring under different weather conditions, with the combination of theoretical analysis and experiments, the electric field monitoring data on the ground and on the top of a building are compared in fair weather and thunderstorm weather respectively in this paper. The results show that: In fair weather, the field distortion due to the buildings is the main influence factor on the electric field monitoring. In thunderstorm weather, the corona ions produced from the ground, besides the field distortion due to the buildings, can also influence the electric field monitoring results.

Based on the dipole technique, the exact expressions and approximate expressions for LEMP on earth surface are derived from the TL model and specified channel-base current described by a pulse function. According to the comparisons between the exact results and approximate results, the waveforms of LEMP and its derivative are similar to the lightning channel-base current and its derivative, respectively. In near-field, the electric field and its derivative waveforms of the approximate results are essentially coincident with the corresponding waveforms of the exact results within 100 m. The magnetic field waveforms of approximate results are essentially coincident with the waveforms of the exact results within 500 m, and the magnetic field derivative waveforms of the approximate results are essentially coincident with the waveforms of the exact results within 200 m. In far-field, the waveforms of the approximate results are essentially coincident with the waveforms of the exact results in the rising edge before the initial peak value. At the distance beyond 100 km, the waveforms of the radiation field component and the scaled channel-base current appear identical. The difference between the derivative waveforms of the LEMP field and the scaled channel-base current in the first three microseconds is slight and can be ignored.

Strong electromagnetic radiation around the conventional lightning rod system exists when it is struck by lightning, and serious electromagnetic interference on sensitive electronic equipments could be caused. A novel active protection method against direct lightning strike is proposed in this paper. The method, which is based on the principle of electrostatic field counteraction and shielding, is aimed at weakening the background electric field near the protection region to eliminate the condition for direct lightning strike there. The protection system is composed of three parts, including the monitoring equipments for atmospheric electric field, the active protection device, and the control system. Two working flow charts of the protection system are presented, and the feasibility of the protection method has been verified by scale-model experiment in the laboratory.