This virtual issue summarizes the most recent research results on various disciplines of electromagnetics and antennas, promoting the new progress of theories and methodologies. 7 papers are selected with domains ranging from antenna design and evaluation, EMC in High-speed railway system as well as analysis and evaluation of electromagnetics disturbance in various scenarios.
1. Large Spaceborne Deployable Antennas (LSDAs)-A Comprehensive Summary
Citation: DUAN Baoyan. Large Spaceborne Deployable Antennas (LSDAs)-A Comprehensive Summary[J]. Chinese Journal of Electronics, 2020, 29(1): 1-15. doi: 10.1049/cje.2019.09.001
This paper provides a survey of research activities of Large spaceborne deployable antennas (LSDAs) in the past, present and future. Firstly, three main kinds of spaceborne antennas, such as solid reflector, inflatable reflector and mesh reflector, are issued by showing the strengths and weaknesses. Secondly, a detailed research situation of LSDAs with mesh is discussed, for majority of the in-orbit large diameter and high frequency antennas are made in this type of structures. Thirdly, new conception of antenna is proposed as it does have both advantages of large aperture (high gain) and high precision (high frequency). Fourthly, the design theory and approach of LSDAs are concerned. It includes thermal-electromechanical multidisciplinary optimization, shaped beam design technique, performance testing technology and evaluation method, passive intermodulation of mesh, and application of new materials. Finally, the ultra large spaceborne deployable antennas of the next generation are presented, such as the deployable frame and inflatable reflector antennas, space-assembled ultra large antennas, smart array antennas and so on.
2. Visualization and Analysis of the Volume Dataset for Time-Varing Electromagnetic Simulation
SHAO Jingxuan, TIAN Ge, HAN Jing, CHANG Liang, CAO Yi, LUO Yanlin
Citation: SHAO Jingxuan, TIAN Ge, HAN Jing, CHANG Liang, CAO Yi, LUO Yanlin. Visualization and Analysis of the Volume Dataset for Time-Varing Electromagnetic Simulation[J]. Chinese Journal of Electronics, 2020, 29(5): 973-981. doi: 10.1049/cje.2020.08.014
The three Dimensional (3D) visualization of time-varying Electromagnetic (EM) data in antenna devices can be used to evaluate various parameters, such as the quality of beams and the power performance of antennas, for optimizing the antenna design. Compared with the single volume data, the time-varying data has characteristics of strong continuity, large scale and multi-variable. It is challenging. We proposed a real-time dynamic rendering method using Compute unified device architecture (CUDA)-based volume rendering algorithm. We designed the opacity transfer function as multiple trapezoid, which represents each energy band, and provided a fusion strategy for a horn-like surface and a EM volume model that considers the contribution of both intersection points of surface with viewing ray and sample points of the volume. We also proposed a framework for time-varying 3D EM datasets. Two assessment tests were conducted by both experts and students. Results showed that our 3D visualization method were effective.
3. Research on Electromagnetic Compatibility of Chinese High Speed Railway System
WEN Yinghong, HOU Weixing
Citation: WEN Yinghong, HOU Weixing. Research on Electromagnetic Compatibility of Chinese High Speed Railway System[J]. Chinese Journal of Electronics, 2020, 29(1): 16-21. doi: 10.1049/cje.2019.09.002
From technology importation to independent innovation, Chinese High speed railway (HSR) has been rapidly developed in the past a few years. However, this technology development mode introduces very complex electromagnetic environment of HSR system, which is based on various equipment with different Electromagnetic compatibility (EMC) design. Consequently, the suppression of electromagnetic disturbance and the electromagnetic protection is becoming an urgent issue for HSR. The characteristics of traction power supply technology, train operation control technology and other core technologies are quite unique in Chinese HSR. In this paper, the EMC and the electromagnetic safety issue of Chinese HSR is discussed, which is derived from technology development mode and core technology characteristics. The limitation of the high speed train's exportation due to the lack of test method for the train's emission is also analyzed. Combining the electromagnetic environment characteristic and the development planning of Chinese HSR, several suggestions in the research of antielectromagnetic interference, electromagnetic protection in the strong electromagnetic field and the whole large system's radiation emission test method are put forward.
4. Analysis of Propagation Characteristics of Electromagnetic Disturbance from the Off-Line of Pantograph-Catenary in High-Speed Railway Viaducts
LI Meng, WEN Yinghong, SUN Xiaokang, WANG Guodong
Citation: LI Meng, WEN Yinghong, SUN Xiaokang, WANG Guodong. Analysis of Propagation Characteristics of Electromagnetic Disturbance from the Off-Line of Pantograph-Catenary in High-Speed Railway Viaducts[J]. Chinese Journal of Electronics, 2020, 29(5): 966-972. doi: 10.1049/cje.2020.08.013
Pantograph arcing caused by Off-line of pantograph-catenary (OLPC) will generate Electromagnetic disturbance (EMD), which will affect train control system and communication system. This paper proposes a simplified model of the train and pantograph to investigate propagation characteristics of EMD from OLPC in the viaduct scenario, containing attenuation law in transverse and longitudinal directions. As a result, the electric field strength of EMD from OLPC increases with distance in transverse direction from 10m to 30m in the viaduct scenario, which is different from the ground scenario. The fitting formulas are found to research the attenuation law at different frequency points. We get the conclusion that the limit and measurement distance is not applicable for the viaduct scenario in current standard. To prove this, measurement in the viaduct scenario is completed, and the plausible evidence to explain the result is discussed. These results are useful in the measurement of radiated emissions, on-board equipment layout and the research of standard in high-speed railway.
5. An APD-Based Evaluation on the Effect of Transient Disturbance over Digital Transmission
GENG Xin, ZHANG Jinbao
Citation: GENG Xin, ZHANG Jinbao, . An APD-Based Evaluation on the Effect of Transient Disturbance over Digital Transmission[J]. Chinese Journal of Electronics, 2020, 29(1): 57-65. doi: 10.1049/cje.2019.09.007
In railway electromagnetic environment, transient disturbances usually degenerate the function of railway wireless communication systems, thus may cause severe security issues. To protect communication services, measurement methodology to characterize disturbances keeps evolving. Nowadays, the statistical characteristics of disturbances, such as Amplitude probability distribution (APD), have been proven more efficient to assess the degradation of digital transmission than Quasipeak detection in most Electromagnetic Compatibility standards. To demonstrate the impact of disturbances on error performance more precisely, a more refined method to estimate Bit error probability (BEP) of digital modulation is necessary. The APD value is ideally obtained with the equivalent bandwidth of the radio service under threat, which means specific apparatus of certain radio service is consequently indispensable. This paper proposes a novel method to estimate the maximum BEP of multilevel amplitude modulations based on APD acquired by standard apparatus. The calculated BEP also provides reference for APD emission restriction.
6. A Novel Approach for On-Site Measurement of Radiated Emission of EMU
LIU Dong, WEN Yinghong, XIAO Jianjun
Citation: LIU Dong, WEN Yinghong, XIAO Jianjun. A Novel Approach for On-Site Measurement of Radiated Emission of EMU[J]. Chinese Journal of Electronics, 2020, 29(3): 574-579. doi: 10.1049/cje.2020.03.013
The main problem in on-site radiated emission test of EMU (Electric multiple unit) is the excess ambient electromagnetic noise due to the complex electromagnetic environment. In order to solve this problem, this paper proposed a novel approach for on-site radiated emission measurement test. A joint algorithm comprise blind source separation and adaptive signal processing is used to suppress the ambient electromagnetic noise. The normalized estimation of ambient electromagnetic noise is obtained by blind source separation algorithm, then the normalized estimation of ambient electromagnetic noise is used as the reference signal to adaptively cancel the ambient noise in the mixed electromagnetic noise, so the estimation of radiated noise of EMU is obtained. The simulation and experiment results showed that the proposed method can effectively suppress the ambient electromagnetic noise, thus realize the accurate measurement of the radiated emission of the EMU.