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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 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.

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.

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.

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.

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.