Experimental Validation of Applicability of Low- Level Test Methods to Assess the Effectiveness of Shielding From High-Power Electromagnetic Fields Vladimir Mordachev 1 , Eugene Sinkevich 1 , Dzmitry Tsyanenka 1 , Oleg Mikheev 2 , Konstantin Sakharov 2 , Alexander Sukhov 2 , Vladimir Turkin 2 , Wen-Qing Guo 3 , Xie Ma 3 , Hao-Yue Zheng 3 1 EMC R&D Laboratory, Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus, emc@bsuir.by 2 All-Russian Scientific Research Institute for Optical and Physical Measurements (VNIIOFI), Moscow, Russia, m12@vniiofi.ru 3 China Electronics Technology Cyber Security Co., Ltd., Chengdu, Taiyuan, China, 18081045600@163.com Abstract — An experimental validation of the linearity of transfer characteristics for elements of the shielding-type protection of an onboard system against high-power electromagnetic fields is carried out by considering the examples of a metal mesh and a braid of a coaxial cable. The validation technique is based on a comparison of the protection element’s amplitude-frequency characteristics obtained at different levels of the electromagnetic test disturbance. The validation is performed for ultra-wideband pulsed disturbance with amplitude up to 50 kV/m, pulse duration of 230 ps, and pulse rise time of 140 ps. The results of the experiments confirmed the applicability of the linear model to the description of the protective properties of shielding elements in the specified range of levels of external disturbance. This fact substantiates the possibility of using the protection element’s frequency characteristics measured at low levels of test disturbance to describe the operation of this element in case of protection against disturbances with amplitudes up to 50 kV/m. Keywords—EMC, electromagnetic shielding, coaxial cables, pulse measurements, electromagnetic transients, IEMI, HPEM I. INTRODUCTION In the design and modernization of mobile objects (aircrafts, cars, ships, etc.), an important task is to ensure the protection of their onboard electronic systems from powerful external electromagnetic (EM) fields [1], [2]. To assess the effectiveness of the use of protection elements (shields, gaskets, filters, limiters, etc.), it is necessary to determine the level of system immunity to EM disturbance before and after applying a protective solution. For the purpose of a preliminary assessment of the effectiveness of a single protection element, a standardized test system [3] is used instead of a real system, which simplifies the comparison of protection elements with each other. Methods of testing the immunity of radio and electronic equipment to radiated electromagnetic disturbances are usually classified into high-level (the level of test field, as a rule, exceeds 100 V/m) and low-level [4], [5]. The advantage of the low-level methods is their simplicity and low cost of experiments as compared to high-level tests. The disadvantage of the low-level methods is that they do not take into account non-linear effects which may occur in the test object under the influence of powerful electromagnetic fields [4]. At high levels of the field, the nonlinear effects can be observed even in objects that are traditionally regarded as linear, for example, in the elements of passive protection of an onboard system from external electromagnetic disturbances. In particular, a diode effect (nonlinearity of the surface properties of materials due to corrosion, moisture, organic contamination) and insulation breakdown may occur in the shields [4]. To confirm the applicability of the results of low-level tests to the description of the test object operation at high levels of disturbance, it is necessary to prove the absence of nonlinear effects in this object at high levels of disturbance. Ultra-wideband EM pulses (UWB EMPs) can be considered as a relatively new type of powerful EM disturbances [2], [5]. The onboard electronic equipment of mobile objects can be efficiently damaged by UWB EMPs [6]. The results of measuring the properties of radio absorbing materials by irradiating them with UWB EMPs are given in [7]. The penetration of powerful UWB EMPs into fortified underground objects was investigated in [8]. The objective of this work is the experimental investigation of the possibility of using a linear model for describing the protective properties of the shielding elements of a system in case of exposure of these elements to UWB EMPs with amplitude up to 50 kV/m. The results of the study will confirm or disprove the applicability of low-level test methods [3], [4], [9], [10] to determine the performance characteristics of shielding protective elements. It was decided to perform the study by consideration of the following typical widely-used shielding-type protection elements as examples: 1) a metal mesh on the aperture and 2) a braided shield (braid) of a coaxial cable. II. TECHNIQUE FOR EXPERIMENTAL VALIDATION OF LINEARITY OF SHIELDS In the framework of linear models of technical means of protection against electromagnetic disturbances, transfer © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. DOI: 10.1109/EMCEurope.2019.8872002