To evaluate the performance of oscillating wall stirrer (OWS) in reverberation chamber (RC), the number of independent stirrer positions, and field distributions (in lessmoded, undermoded, and overmoded frequency regimes) are discussed in detail in this work. For the estimation of independent stirrer positions, correlation matrix method (CMM), i.e., threshold-dependent correlation matrix defined by Pearson correlation coefficient, is used to determine the number of independent stirrer positions, where experimental comparative analysis between autocorrelation coefficient in IEC 61000-4-21 and CMM is presented, and the corresponding results provide a reasonable explanation for the overestimation of independent stirrer positions. For the field distributions, parameter $M$ in Bessel $K$ distribution, related to the number of excited modes within $Q$ -bandwidth, is adopted to assess the quasiwall-like behavior of OWS in lessmoded, undermoded, and overmoded RCs, respectively, and the results show that OWS can distribute the field energy that was not sufficiently stirred with a higher probability ( $>$ 50%) at undermoded frequencies.

The interconnected systems (ISs) are commonly exposed to electromagnetic environments with different maximum field levels, and the measurement technique on how to perform radiated susceptibility (RS) test is one of the most attractive research topics of the electromagnetic compatibility (EMC) community. In this work, the dual reverberation chamber (DRC) is used to reveal the potential EMC issues of the IS, which also provides a comparison with the RS tests performed in a conventional RC. By using a typical IS on the ship, we highlight the evidence supporting IS to conduct the RS tests in the DRC. Taken together, the results show that the IS will be more sensitive within the DRC and expose more acute EMC problems on one hand; on the other hand, the IS also presents a larger probability of sensitivity.

The ship system should be compatible with the electromagnetic environment (EME) in which it works. The evaluation of electromagnetic environmental effects (E3) is the premise and means to realize this goal. A method for E3 evaluation of ship system based on impact degree is proposed. The normalized index is used to synthesize the E3 impact degree of different types of E3 elements and different types of susceptible receptors with this method. The mathematical model and calculation method are presented. Through the comparison of the two groups of ship system design schemes before and after the improvement, taking the effects of electromagnetic interference, external radio frequency, radiation field hazards and antenna coverage performance as examples, the numerical results of various effects and the total E3 impact degree are calculated respectively. The results show that the method can support the balance and optimization of ship system E3 multi-index design, and the actual effect is obvious.

In this article, a method combining array signal processing and adaptive noise cancellation is proposed to suppress the ambient interferences of in-situ measurement. First, the directions of arrival and classes of all signals are obtained by performing blind source separation and sparse reconstruction on the received signals. Then, the received signals are reused to form two different data channels. In both channels, the interferences that are coherent with the radiated signals of the equipment under test and have larger amplitudes are eliminated based on null trap forming, whereas the coherent interferences with smaller amplitudes are ignored after being attenuated. Besides, the other interferences are suppressed by the adaptive noise cancellation based on their correlation in the two channels. For transient signals, overlapping window technique is used to avoid the losses of the spectrums. Each frame of the signals is cyclically extended to provide sufficient points for adaptive noise cancellation. The proposed method achieves the suppression of multisource ambient interferences with fewer array elements. Simulation and experiment results are given to verify the effectiveness and accuracy of the proposed method.

More and more EMC tests have shown that the radiated emission problems of the equipment under test mainly concentrate on the intercon- nected power cables and cable connectors. Measurement of shielding performance is a prerequisite for quantitative and qualitative evaluation of the frequency-dependent characteristic of braided-shield power cables and cable connectors. Due to the asymmetric geometric structures of these cable assemblies, compared with the coaxial and symmetrical communication cables, the commonly used transfer impedance testing methods may not be suitable. In view of this, several improved simple and effective measurement methods, including transfer impedance and shield reduction factor testing methods, were proposed in recent years. These methods, based on the equivalent circuit model of the characteristic parameters, provide good repeatability for the measurement of shielding performance. This paper presents an overview analysis of various measurement techniques for shielding performance of power cables and cable connectors, highlights some of its equivalence principle in measurement setups, and showcases a brief comparison between transfer impedance and shield reduction factor.

Shielding effectiveness (SE) evaluation of electrically large enclosures within reverberation chambers (RCs) is standardized procedure for electromagnetic compatibility (EMC) applications. In this work, the potential relationship between SE and electromagnetic resonances has been investigated with respect to the ambiguity in definition of SE for the international standards, e.g., IEC 61000-4-21 or IEEE Std 299.1. From a statistical point of view, we derive the expansions of SE defined by the ratio of the maxima and the averages. To evaluate SE more prudently as well as to obtain a much smaller uncertainty, we can make the tradeoffs for SE, which should be defined as the ratio of the averages for the overmoded frequency and the ratio of the maxima for the undermoded using a common criterion aimed to discriminate the electromagnetic field behavior between the undermoded and the overmoded and also verify the corresponding results by numerical simulations and measurement performed in RC.