Enlarging or reducing the antenna beam width of antennas can improve the positioning capability of detection systems. A miniaturized and easily fabricated ultra-wideband (UWB) antenna system for long-distance electromagnetic detection is proposed in this article. Two ultra-wideband Vivaldi antennae were designed. One was the transmitting antenna with a beam width of 90° or above, the other was a narrow beam antenna array with beam width less than 10°, as a receiving antenna. Both proposed antennae feature broadside gain diagrams with stable radiation patterns and wideband impedance matching in the frequency range between 2.5 GHz and 4 GHz. After detecting their frequency and time-domain behaviors, the detection system can achieve measurements covering a radius of 30 m.

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.

316L stainless steel foams (SSFs) are fabricated successfully by polymeric sponge impregnation technology. The effects of mass fractions of PVA and powder on LOAD in impregnated sponge samples are investigated, and the effects of sintering temperature on apparent density, open porosity and bending strength of SSFs samples are also discussed. The experimental results show that the impregnated sponge samples may hold excellent 3D open-cell network structure and uniform muscles when the mass fractions of PVA and powder in slurry are kept in 9-13 % and 52-75% respectively; with rising the sintering temperature, the apparent density and bending strength of SSFs gradually increases, the open porosity reduces. After the temperature exceeds 1260°C, the bending strength reduces oppositely. A stainless steel foam sample with open porosity of 81.4% and bending strength of about 56.8 Mpa can be obtained after sintering at 1260 °Cfor 30min.

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.