Aiming at the evaluation of the shielding effectiveness (SE) of materials against high-intensity electromagnetic pulse (EMP), the shielding mechanism in the frequency domain is investigated, and the factors that determine SE such as conductivity, thickness of material, and test frequency are analyzed. The attenuated waves of solid and perforated plate materials irradiated by EMP are simulated in CST. The results show that the two materials exhibit low-pass and high-pass filtering characteristics, respectively, which lead to a big difference in the transmitted waves (rise time and pulse width). Based on this, a time domain SE test method using coaxial flange is proposed which can obtain the incident and the transmitted and reflected waves, and the time domain SE of graphenes with different thicknesses (80, 100, 200, and 300 μm) are measured. The characteristics of the reflected and transmitted waves are analyzed in detail, and the change regulations comply with the theoretical shielding model well. The peak value SE and energy density SE, respectively, are calculated. Furthermore, the frequency domain SE can be obtained through the Fourier transform, so the method has a wide application in material SE performance evaluation against high-intensity EMP.

In this paper, balanced tri- and quad-band bandpass filters (BPFs) with high selectivity and controllable center frequencies and bandwidths are proposed. In the tri-band BPF design, two differential-mode (DM) passbands are formed by utilizing a stub-loaded resonator (SLR) and a uniform impedance resonator (UIR). The coupling structure of the proposed BPF realizes the third DM passband. Moreover, the center frequencies and bandwidths of the three DM passbands can be controlled by the lengths of resonators and the gaps between the resonators. In order to improve the DM selectivity further, the source-load-coupled structure is introduced. In addition, common-mode (CM) suppression is achieved by using L-shaped balanced microstrip line to slotline transition structures, achieving the independence between CM responses and DM ones. Therefore, the design procedure can be simplified greatly. In order to validate the practicability, one balanced tri-band BPF operating at 2.5, 3.5 and 4.5 GHz is designed and fabricated. Moreover, by adding a short stub to the UIR located in the symmetrical plane, one flexible resonance frequency is generated, which is used to design the balanced quad-band BPF. By manufacturing and measurement, the measurement and simulation are in good agreement.

The transient surface current density reflects the external coupling of the electromagnetic pulse (EMP) to the tested device. In this paper, the generation mechanism and measurement principle of conductor surface current density are introduced, and the surface current density distribution irradiated by EMP on a typical aircraft structure is simulated and analyzed. The traditional surface current density is usually measured by B-dot antenna, but its output signal is the differential of the measured signal, so additional integrators or numerical integration of the measured data are required. In this paper, a self-integrating surface current sensor based on optical fiber transmission is designed based on the shielded loop antenna with gap structure. The output signal is the real signal waveform to be measured. Compared with coaxial cables, integrated optical fiber transmission improves the anti-interference ability of long-distance transmission signals. At the same time, the design process of the sensor is introduced in detail. The bandwidth of the sensor is 300 kHz~500 MHz, the sensitivity is calibrated at 1.23 (A·m⁻¹)/mV, and the dynamic range is ±25~1400 A·m⁻¹ (35 dB). The surface current of a metal plate is measured in a bounded wave electromagnetic pulse simulator using a detector developed in this paper. The test results show that the developed sensor has good engineering applicability.