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25 June 2020, Volume 40 Issue 3 Previous Issue    Next Issue

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Influence of 3D regular surface morphology on secondary electron emission ZHANG Na, CUI Wanzhao, CAO Meng, WANG Rui, HU Tiancun 2020, 40 (3):  1-7.  doi: 10.16708/j.cnki.1000.758X.2020.0025 Abstract ( 450 )   PDF (3603KB) ( 340 )   Save It has been applied in many fields to customize specific surface morphology to control secondary electron emission of materials.The regular surface morphology can easily reveal the influence of the suppression and the influence mechanism on the secondary electron emission. Meanwhile, photolithography, plasma etching and other processes can better achieve the specific design of regular morphology. Therefore, custom regular morphology is often used in the initial research stage of multipactor or in the process of principle experimental verification. Taking the threedimensional cylindrical hole as an example, multi-generation Monte Carlo method which considers multiple interactions between electrons and complex surface morphology was used to systematically study the influence of regular morphology parameters such as depthwidth ratio and duty cycle ratio on secondary electron yield (SEY), secondary electron spectrum (SES) and emission angle distribution. It was found that the larger the depthwidth ratio of regular morphology is, the wider the SES broadening, the stronger the selectivity of the morphology to emission angle, and the better restraint effect of SEY, but the restraint effect is not indefinite. When the morphology does not overlap, SEY can also be effectively reduced by increasing the duty cycle ratio. However, due to the relatively small proportion of emitted electrons of the cylindrical hole compared with flat surface, the SES and the emission angle distribution is close to flat surface. The secondary electron emission properties of regular morphology obtained in the paper provide a reference for the comprehensive evaluation of its influence on multipactor effect. Related Articles | Metrics

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Analysis of low passive intermodulation filter used in spacecraft WANG Qi, CUI Wanzhao 2020, 40 (3):  8-12.  doi: 10.16708/j.cnki.1000.758X.2020.0026 Abstract ( 472 )   PDF (2644KB) ( 551 )   Save With the development of spacecraft payloads toward high power and miniaturization, the problem of passive intermodulation (PIM) of high power filters has become an important issue that restricts the development of spacecraft payloads. The factors of generating passive intermodulation in highpower coaxial filter used in spacecraft were researched and explored which found the influence rules on passive intermodulation of different surface coating treatments and adjusting ways of screws by different materials. In this paper, a S-band low-passive intermodulation coaxial filter was designed according to the contact made between the inner conductor and the feeding pole of the dielectric isolated coaxial connector. Compared with the traditional coaxial filter,the passive intermodulation of the new one can be effectively reduced by 20dB. This shows that the method is effective to reduce the passive intermodulation of high power microwave components and can be used in high power microwave and ground mobile power components. Related Articles | Metrics

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Research on passive intermodulation based on broadband modulation signal LI Yanping, HUANG Hao, HE Jie 2020, 40 (3):  13-18.  doi: 10.16708/j.cnki.1000.758X.2020.0027 Abstract ( 503 )   PDF (1204KB) ( 271 )   Save With the extensive use of transmitter-recevier sharing and digital modulation (BPSK,QPSK) technologies in satellite communication, there are insufficient verification problems in the original continuous wave (CW) and passive inter modulation (PIM) test system. In this paper, a broadband digital signal PIM test method was designed by using the channel power to test PIM. The test results show that digital modulation PIM values of both BPSK and QPSK signals are higher than the CW carriers by 2~9 dB. Considering the operational reliability of the satellite, the digital modulation working mode was adopted to improve the original test system and the new test is closer to the pracical work, which improves the reliability of ground verification. Related Articles | Metrics

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Design of L-band space based wideband low noise amplifier chip ZHAO Bochao, XU Hui, YIN Pan, HE Juan, ZHANG Dawei, XU Xin 2020, 40 (3):  19-24.  doi: 10.16708/j.cnki.1000.758X.2020.0028 Abstract ( 522 )   PDF (4040KB) ( 453 )   Save An L-band monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) used in satellite microwave receiver was developed with 0.25μm GaAs pseudomorphic high electron mobility transistor (pHEMT) technology. The current reuse topology structure was used to achieve lower current and the precious satellite power resource was saved. The two-stage negative feedback was applied to increase stability and gain flatness, and then satellite communication quality was improved. The constant current source bias stabilized the working conditions where current was slightly influenced by the processes. The test results show that the working current is below 35mA, from 0.9GHz to 1.8GHz, the gain is higher than 33dB with gain flatness less than 0.5dB, the noise figure is below 0.6dB, and the size of the LNA chip is 2.0mm×1.3mm. The circuit can meet the requirement of high performance and miniaturization in space application. Related Articles | Metrics

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Research on performance of TWF composites for space antenna LI Yichen, SONG Yanping, HU Fei 2020, 40 (3):  25-35.  doi: 10.16708/j.cnki.1000.758X.2020.0029 Abstract ( 514 )   PDF (6291KB) ( 307 )   Save Using a carbon fiber triaxial woven fabric (TWF) as a reinforcing material and compounding it with a suitable flexible matrix material, a carbon fiber three-directional woven composite shell film structure is formed，featuring both flexibility and rigidity. As a satellite antenna reflector, it is a new type of high precision deployable antenna implementation.  The mechanical properties of silicone matrix TWF composites were studied. Using the composite mesoscopic method, the material properties of the homogeneous fiber bundle were obtained from the material properties of the fiber and the matrix. Then, considering the fiber bundle interlacing (undulation fluctuation), a unit cell finite element model composed of the fiber bundle was established. Homogenization analysis of the unit cell finite element model was carried out, applying periodic boundary conditions, and finally obtaining equivalent homogeneous material properties. In order to meet the high performance requirements of antenna reflectors, the influence of carbon fiber type and fiber volume content on the equivalent performance of unit cell was analyzed. The mechanical properties of the material were studied, which provides a theoretical basis for its application to large deployable highprecision antenna reflectors in the future. Related Articles | Metrics

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Design of satellite-borne microwave photonic mixer based on DDMZM HUI Jinxin, ZHAO Ying, DENG Xiangke, ZHENG Feiteng, SUN Shufeng 2020, 40 (3):  36-42.  doi: 10.16708/j.cnki.1000.758X.2020.0030 Abstract ( 543 )   PDF (2308KB) ( 500 )   Save Due to the influence of distributed parameters on microwave components, there is certain frequency selectivity, and it is difficult to achieve the broadband and multi-band compatible frequency conversion system, which can no longer meet the needs of the high-throughput satellite communication payload. Microwave photonics technology provides the possibility of realizing high-throughput satellite communication needs with its advantages of large bandwidth and no frequency selectivity. Based on dual-drive Mach-Zehnder modulator (DDMZM), the solution of the frequency conversion unit of the satellite communication system was explored. Through theoretical analysis of the link model, the software VPI was used to simulate and optimize the link to find the best offset point of the DDMZM. The experimental results show that when the modulator is biased at the minimum point, the frequency conversion efficiency is high, and it has certain carrier suppression function, which can achieve broadband, multi-band and anti-interference performance,and is superior to microwave frequency conversion performance. Related Articles | Metrics

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Research progress of constellation backup strategy WANG Xuyu, HU Min, ZHAO Yulong, XU Jiahui 2020, 40 (3):  43-55.  doi: 10.16708/j.cnki.1000-758X.2020.0031 Abstract ( 595 )   PDF (1857KB) ( 927 )   Save In view of the phenomenon that constellation service performance worsens due to operation or failure of constellation satellite in orbit, the research progress of constellation backup strategy was reviewed. Firstly, the basic situation and backup status of navigation constellation and communication constellation were summarized. The backup strategies of different constellations were concluded. Secondly, three different constellation backup strategies,i.e., in-orbit backup, parking orbit backup and ground backup, were highlighted. Then in terms of satellite failure, satellite reliability, satellite availability, constellation state probability and constellation system availability, the research progress in the key factors of the constellation backup strategy were reviewed. Thirdly, the main models and methods for the analysis of constellation backup strategy were introduced, including Petri nets, Markov chains and inventory theory. Finally, the future research directions of constellation backup strategy were prospected. Related Articles | Metrics

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Sliding mode control based on fuzzy neural network for variable structure spacecraft WANG Ran, ZHOU Zhicheng, QU Guangji, CHEN Yujun 2020, 40 (3):  56-63.  doi: 10.16708/j.cnki.1000-758X.2020.0032 Abstract ( 478 )   PDF (3275KB) ( 341 )   Save Variable structure spacecraft is an important development direction of astronautics. The mass distribution of the spacecraft will change significantly during the configuration variation, and this will generate new problems of dynamic modeling and controller design. To solve these problems, the hybrid coordinate method and Lagrange equation were used to build the dynamic model of the spacecraft, and changing rule of the dynamical parameters was approximated by several typical working conditions. Sliding mode controller was designed to control the attitude during the variation of the spacecraft. To improve the adjustment of the controller, fuzzy neural network(FNN) was designed to adjust the parameters of the controller adaptively. The radial-based function (RBF) neural network was designed to approximate dynamic model, and thus the relationship between the control torque and attitude variation was obtained, which was used to optimize the FNN. The attitude of the variable structure spacecraft during the structure variation with no control, sliding mode control and fuzzy neural network was acquired in simulation. The results verify the effectiveness of the fuzzy neural network adaptive sliding mode controller, and comparisons were made to verify the good properties of the proposed controller. Related Articles | Metrics

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Trajectory optimization and control analysis of folding wing aircraft YANG Bo, ZHU Yichuan, WEI Yanming, FAN Zichen 2020, 40 (3):  64-75.  doi: 10.16708/j.cnki.1000-758X.2020.0033 Abstract ( 524 )   PDF (8059KB) ( 290 )   Save In view of the problem of hypersonic aircraft in adjacent space, a folding wing aircraft was designed, which can adapt to various flight states and maintain the optimal aerodynamic characteristics. According to the characteristics of hypersonic glide in adjacent space, Gaussian pseudo-spectral method was used to optimize the trajectory of fixed-wing aircraft and fold-wing aircraft. By comparing the capability of range and the ability of avoiding heat flow of fold-wing aircraft with that of traditional fixed-wing aircraft, a trajectory optimization idea of comprehensive target was proposed. Compared with the traditional fixed-wing aircraft, the designed folding wing aircraft has better performance and is more suitable for the adjacent space environment. It improves the range by 17.67% and reduces the peak heat flow rate by 35.72%. It is verified by the design and simulation of the control system. The simulation results show that the maneuverability of the variant aircraft is improved significantly compared with that of the fixed-wing aircraft. Related Articles | Metrics

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Effect analysis of cable fracture during two-dimension two-step solar wing deployment DONG Fuxiang 2020, 40 (3):  76-82.  doi: 10.16708/j.cnki.1000-758X.2020.0034 Abstract ( 404 )   PDF (5215KB) ( 379 )   Save The effect of cable fracture at different locations on solar wing deployment was presented, to identify their key parts and predict their deployment failure mode in orbit. The mechanics models of closed cable loop were established with considering cable fracture effects, and the force and moment at the wheel of closed cable loop (CCL) were formulated. The method of angle trigger constraint elimination (ATCE) was presented to solve the continuous simulation problem of second deployment of solar wing. The dynamics equations of the 2nd deployment of solar wing were derived, and the deployment angle, deployment configuration, and tension forces on other cables were analyzed at the different locations of cable fracture. The analysis indicates that the nearer cable fracture of cable closed loops from satellite body will make bigger effects to solar wing deployment; the fracture of cable closed loop at the yoke may make the solar wing fail to deploy. Related Articles | Metrics

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GEO satellite communication link budgets calculation and analysis XU Ting, LAN Hai, ZHANG Hongjiang 2020, 40 (3):  83-92.  doi: 10.16708/j.cnki.1000-758X.2020.0035 Abstract ( 1293 )   PDF (3338KB) ( 2285 )   Save As an important technology, satellite-ground link budget calculation is the theoretical basis of satellite communication system designing which directly decides the link availability. As there are many factors which may affect the satellite link, any unreasonable factor in the design would make the whole satelliteground link unavailable and leads to a big loss. Moreover, there is no ideal satellite link situation unless overlooking some factors, which is also a difficulty during the link budget calculation. Based on the international common calculating method, GEO satellite link was analyzed thoroughly, separating the whole link into uplink and downlink. Then a practical example was analyzed and calculated according to the project experience in LAOSAT Company. At last, different reasonable designing methods in terms of different link configurations were obtained, which could be the references to link calculation and analysis of GEO satellite communication. Related Articles | Metrics

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System design and implement of ground electrical performance testing for spaceborne camera ZHANG Yalin, DU Yiqiang, WANG Chun, LIN Zhe, SUN Weijian 2020, 40 (3):  93-99.  doi: 10.16708/j.cnki.1000-758X.2020.0036 Abstract ( 381 )   PDF (1489KB) ( 251 )   Save Based on the characteristics of the new camera with complex structure and multiple loads,a ground test system for the electrical performance of a new satellite camera was designed and implemented.The design requirements of the ground test system were analyzed and summarized,and for the comprehensive requirements of the new camera test,the simulation interface of the whole satellite and multiple loads was designed and implemented.Aiming at the reliability requirements of the new camera test,the design method of redundant network switching test system was proposed and the problem of database access conflict was solved. In order to meet the safety demand of the new camera test, test methods for redundant links and error injection were proposed. The system has successfully completed the development and delivery of a hightorbit spaceborne camera. The experimental results indicate that this system works stably, and the bit error rate is 0 under 72 hours of continuous testing. The system can meet the testing requirements of comprehensiveness,reliability and safety of new type spaceborne camera. Related Articles | Metrics

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A momentum wheel health ranking method based on fuzzy clustering model JI Ye, CUI Zhen, WANG Xuetao, YAN Rong, LIU Yifan 2020, 40 (3):  100-106.  doi: 10.16708/j.cnki.1000-758X.2020.0037 Abstract ( 360 )   PDF (1197KB) ( 432 )   Save Based on the fuzzy clustering analysis, a momentum wheel health ranking method was proposed. The ground test data and on-orbit data of 50N·m·s momentum wheel in actual model tasks were selected. After the data were processed, the instantaneous dynamic speeds of the momentum wheels in closed loop conditions were studied, then the data were converted into the fuzzy similarity matrix by the correlation coefficient method, and cluster analysis was conducted for the maximum threshold of risks. Meanwhile, the maximum threshold was used as a criterion to design the judgment criteria. The data of the four momentum wheels were used to verify the practicability of the method and compared with the kurtosis test method. The results show that this method can accurately rank the health of momentum wheels. Related Articles | Metrics

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Ballistic coefficient estimation method based on TLE and application analysis ZHANG Wei, CUI Wen, ZHANG Yuwei, LIU Xing, ZHU Jun 2020, 40 (3):  107-113.  doi: 10.16708/j.cnki.1000-758X.2020.0038 Abstract ( 805 )   PDF (3008KB) ( 561 )   Save In order to meet the requirements of research which use two line element (TLE) as data source, ballistic coefficient estimation methods based on the variation in mean semimajor axis derived from TLE were studied. A direct estimation method based on two TLEs was introduced, and the influence of the TLE interval on the ballistic coefficient result accuracy was analyzed. In order to reduce the influence of outliers, an iterative estimation method based on multiple TLEs was proposed. Comparative analysis was made for these two methods. The results show that these two methods have their own advantages and disadvantages. The ballistic coefficient results estimated by the iterative method have higher stability and are less affected by the TLE accuracy. Due to the shorter data interval, the estimation results using the direct method respond more accurately to the short-term orbital variation characteristics, and this method is recommended to be used in the last phase of re-entry. Related Articles | Metrics