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2022, 37(3): 1-2.  
Abstract(27) FullText HTML(15) PDF(18)
Preliminary analysis of daytime electron density in the ionospheric E-F valley based on the Qujing incoherent scatter radar observations
DING Zonghua, DAI Liandong, YANG Song, MIAO Jiansu, WU Jian
2022, 37(3): 357-363.   doi: 10.12265/j.cjors.2021091
Abstract(326) FullText HTML(103) PDF(28)
The ionospheric E-F valley is difficult to be measured due to its low ionisation. This paper presents the preliminary analysis of daytime electron density profiles in the E-F valley between 120 and 200 km measured by the Qujing incoherent scatter radar. These electron density profiles in the E-F valley depend greatly on the local time and season. There are two kinds of typical E-F valley profiles, of which one has the obvious valley structure in 120−160 km with the altitude of the minimal electron density 134−144 km and the other has a wider valley with a smooth profile between 120 and 150 km and monotonically increasing above 160 km, the valley is located at about 130 km. The electron density in 120−130 km shows the obvious enhancement after the solar flare burst below the altitude of 129 km and sudden enhancement in the D region, and no obvious variations above 134 km, which may be related to the solar X-ray fulx enhancement. The electron density in 139−158 km shows no obvious variations and some enhancements in 177−196 km in the geomagnetic storm event, which may be related to the oxygeon content enhancement.
Research on the consistency and coherence of the ionospheric short-wave transmission channel based on multi-station sounding
LIU Tongxin, ZHOU Chen, YANG Guobin, JIANG Chunhua, ZHAO Zhengyu, ZHANG Hong
2022, 37(3): 364-371.   doi: 10.12265/j.cjors.2021127
Abstract(190) FullText HTML(95) PDF(27)
For distributed high-frequency radar system and short-wave time difference of arrival location methods, the consistency and coherence of characteristic parameters of the adjacent ionospheric short-wave channels need to be considered as key factors. In this paper, a multi-station short-wave ionospheric channel oblique sounding experiment with synchronous networking is carried out preliminarily in Wuhan, Daofu, Leshan by employing the equipments with independent intellectual property. The results show that, when the sun and geomagnetic activity are calm, for the two similar links of Wuhan-Daofu and Wuhan-Leshan, the statistical characteristics of the channel parameters such as the diurnal variation of channel group delay, group delay broadening, Doppler shift and Doppler broadening are basically equal. The signals received by Daofu and Leshan from Wuhan can still get obvious correlation peaks after being propagated through the ionosphere. Meanwhile, they have the linear phase change laws and a stable phase difference. In this paper, it is proved that the adjacent short-wave ionospheric channels have good parameter consistency and coherence over a short distance range.
Path loss prediction based on machine learning and satellite image
HE Danping, XU Zhuocheng, CAO Huiyun, YIN Yue, WU Lina, GUAN Ke
2022, 37(3): 372-379.   doi: 10.12265/j.cjors.2021064
Abstract(342) FullText HTML(133) PDF(30)
Based on back propagation neural network (BPNN), this paper establishes a channel model. The color information of red, green and blue channels (RGB) in satellite images is used to characterize the environmental characteristics of radio wave propagation path in wireless communication. We build the data set combining the color information and the distance between the measuring points and the base station and iteratively train the parameters of the net to predict the propagation path loss. The results given by the channel model show that the correlation coefficient between the predictions and the measured data reaches 0.83, absolute mean error is controlled at 0.66 dB, and standard deviation is controlled at 6.65 dB, which indicate that this model can reliably predict the propagation path loss of radio waves in wireless communication in the absence of a detailed model and material parameters of a certain scene. In the end, the model is compared with the traditional channel modeling method in many aspects. The results show that the model can provide prediction results that are slightly different from traditional channel modeling methods under the same computing resources, while greatly reducing the required time. The model can quickly predict propagation path loss in the optimization of wireless communication network system.
Test study on magnetic saturation effect of magnetic shield in low-frequency pulsed magnetic field
PAN Zheng, LI Yuebo, XIONG Jiuliang, SHI Lihua, YAN Minhua
2022, 37(3): 380-387.   doi: 10.12265/j.cjors.2021130
Abstract(256) FullText HTML(104) PDF(22)
In view of the magnetic saturation problem that may exist in the magnetic shield in the low-frequency pulsed magnetic field environment, the magnetic saturation effect study was carried out by using the test method. It is confirmed that the conventional engineering shield can reach the magnetic saturation state in the low-frequency pulsed magnetic field environment. The magnetic saturation law was obtained by observing the change of the shielding effectiveness of the shield, and the influence of the magnetic saturation effect on the shielding effectiveness was analyzed in relation to the material permeability of the shielding body, the thickness of the shell, the external dimensions and other parameters. Studies show that the low-frequency pulsed magnetic field can make the shield reach a state of magnetic saturation, and the shielding effectiveness of the magnetic shield shows obvious dynamic change characteristics, and has a similar change trend to the permeability of the shield shell; For a shield with a shell thickness of less than 2 mm and a length, width and height of about 2 m×2 m×2 m, in a magnetic field environment with a rise time of 300 μs and a duration time of 1.2 ms, the magnetization field strength to reach magnetic saturation is about 10 mT, and the degree of magnetic saturation has a negative correlation with the magnetic permeability and external dimensions, and has a positive correlation with the thickness of the shell. The research results are consistent with the theoretical analysis conclusions, which can provide references for the scientific and reasonable design of magnetic shields and have high engineering application value.
Research on non-ideal waveform modulation of time modulation array antenna
LUO Yuchuan, XIANG Lei, GAO Yanchang, NI Gang, CHEN Jingfeng, HE Chong, LIANG Xianling
2022, 37(3): 388-393.   doi: 10.12265/j.cjors.2021148
Abstract(334) FullText HTML(110) PDF(39)
In this paper, aiming at the non-ideal characteristics of the radio frequency switch in the time-modulated array antenna, the harmonic characteristics of various modulation waveforms are studied. First, the Fourier coefficients of the asymmetric trapezoidal/raised cosine waveforms are deduced, and the influence on amplitude, phase and energy proportion of two waveforms are analyzed. On this basis, an experimental modulation waveform are obtained through experiments, and trigonometric polynomials are used to fit the rising and falling edges of the real modulation waveform. Finally, the difference between various waveforms and harmonics is discussed. The results show that compared with existing modulation waveforms, the modulations of the asymmetric trapezoidal waveform, asymmetric raised cosine waveform and the fitted waveform proposed in this paper are closer to real waveform.
Design principles of reconfigurable power dividers from S to millimeter waveband
GAO Weinan, GENG Junping, ZHOU Han, CHEN Nian, WANG Kun, REN Chaofan, SU Da, HE Chong, LIANG Xianling, JIN Ronghong
2022, 37(3): 394-404.   doi: 10.12265/j.cjors.2021049
Abstract(96) FullText HTML(39) PDF(30)
To satisfy the requirements for millimeter-wave reconfigurable communication systems, we designed a millimeter-wave reconfigurable Wilkinson power divider. At first, we designed an S band reconfigurable Wilkinson power divider based on PIN diode, and then the design principle was used in K/Ka band. We studied the effects of the parasitic parameters of PIN diode and the best matching method with parameter extracting, and designed a K/Ka band reconfigurable power divider. We conducted simulation and measurement, and the measurement results show that in the working band, in two-way mode the insertion loss from port 1 to transmission ports (port 2 and port 3) is below 4.92 dB and the isolation between two transmission ports is above 15.8 dB; in one-way mode the insertion loss is below 1.65 dB and the isolation between port 1 and the isolation port is above 22.4 dB. The measurement and simulation results generally agree with each other. Considering the effects of the parasitic parameters of PIN diode, and using EM/circuit co-simulation, we designed a reconfigurable power divider based on PIN diode in K/ Ka band with is accurate, simple and suitable for applications in reconfigurable systems.
Design of X-band power divider based on slow-wave substrate integrated waveguide
HUANG Wen, CHEN Xiao, REN Yi, ZHOU Zhengyi, ZHU Hongyu, ZENG Ting
2022, 37(3): 405-410.   doi: 10.12265/j.cjors.2021142
Abstract(457) FullText HTML(166) PDF(37)
To solve problem that it is not easy to account both broadband and miniaturization in the design of traditional substrate integrated waveguide (SIW) power divider, a power divider based on slow-wave substrate integrated waveguide (SW-SIW) is proposed in this paper. The slow-wave structure units composed of microstrip lines are loaded on the metal surface of SIW instead of the continuous metal surface of traditional SIW. Compared with SIW of the same size, the cut-off frequency of SW-SIW is decreased by 40%, which can reduce the lateral size of the substrate integrated waveguide. When SW-SIW and SIW have the same phase shift, the longitudinal dimension of SW-SIW is smaller than SIW. The proposed power divider based on SW-SIW is achieved a size reduction with a wide bandwidth. The measurements show that the power divider has a bandwidth of 43.2% from 8.25 GHz to 12.8 GHz with the reflection coefficient |S11| less than −10 dB. The phase consistency is good, and the miniaturization effect is obvious, so the proposed power divider is suitable for the application of compact microwave radio frequency front-end.
An optimal preconditioning scheme for the discontinuous Galerkin solution of multi-region target scattering problems
ZHANG Huiwen, HUANG Xiaowei, WU Biyi, SHENG Xinqing
2022, 37(3): 411-418.   doi: 10.12265/j.cjors.2021065
Abstract(212) FullText HTML(44) PDF(25)
The electromagnetic scattering from multi-region targets with homogeneous dielectrics and metals are of significant importance in various microwave applications from antenna design to radar imaging. Aiming at the multi-region target scattering problems, the discontinuous Galerkin(GD) solution in the surface integral equation(SIE) method of moment(MoM) is studied, and an optimized distance sparse preconditioner(O-DSP) is proposed. Based on the different matrix characteristics associated with different integrodifferential operators, the proposed preconditioner is constructed by adopting customized sparse strategies, and the sparsity of the preconditioner is further improved. Numerical studies demonstrate that, compared with the conventional DSP, the number of nonzero elements in the proposed precondition matrix is nearly halved, while maintaining similar convergence rate.
Regional high spatial and temporal resolution ionospheric TEC map reconstruction base on DCT-PLS algorithm
OU Ming, CHEN Longjiang, WU Jiayan, ZHEN Weimin, LYU Menghai
2022, 37(3): 419-425.   doi: 10.12265/j.cjors.2021211
Abstract(238) FullText HTML(91) PDF(19)
Ionospheric TEC map with high temporal and spatial resolution plays an important role for the analysis and modeling of small and medium scale ionospheric disturbances. Based on the monitoring data of the crustal movement observation network of China(CMONOC) and the IGS, the reconstruction of high spatial and temporal resolution TEC maps (1°×1°×15 min) in China and its surrounding areas is realized based on penalized least square regression and discrete cosine transform (DCT-PLS) algorithm. The results are compared with the data of MIT Madrigal high precision vertical TEC data in 2014 and 2018. Compared with GIM data from CODE, the consistency and stability of vertical TEC given by DCT-PLS algorithm is obviously improved. The average error of TEC is reduced from 3.9 TECU to 2.0 TECU, and the standard deviation is reduced from 3.7 TECU to 2.7 TECU. The results of ionospheric reconstruction during a magnetic storm in September 2017 show that this algorithm can better reproduce the ionospheric disturbance structure characteristics during the magnetic storm, and the related results can provide theoretical support for the realization of regional high-resolution ionospheric monitoring and application.
Typical event observation of the tri-band beacon onboard the CSES (ZH-1) satellite
LU Hengxin, SHEN Xuhui, ZHAO Shufan, LIAO Li, LIN Jian, HUANG Jianping, ZEREN Zhima, SUN Fang, GUO Feng
2022, 37(3): 426-433.   doi: 10.12265/j.cjors.2021106
Abstract(322) FullText HTML(170) PDF(32)
Tri-band beacon (TBB) transmitter has been carried on the China Seismo-Electromagnetic Satellite (CSES), based on the ground-based receiving system, it can be used to provide a quick ionospheric tomography. The main purpose of this work is to check the application effect of the TBB payloads. The study shows that during 2018−2019, the semiannual variations of ionospheric F2-layer can be observed clearly in NmF2 data, and we also detected the ionosphere perturbations induced by the geomagnetic storm occurred on August 26, 2018, which has been proved to be a positive storm event using electron density data. All these results indicate that TBB observation can provide accurate observation data of the ionosphere and be used effectively to monitor the ionospheric changes during the space weather events.
Frequency planning method for joint operations based on multi-objective optimization
LIU Ming, ZHA Song, HUANG Jijun, LIU Jibin, HAO Xiedong, MA Chen
2022, 37(3): 434-442.   doi: 10.12265/j.cjors.2021060
Abstract(521) FullText HTML(133) PDF(24)
In order to describe the joint operation frequency planning problem comprehensively, the multi-objective optimization theory is introduced, and a multi-objective joint operation frequency planning model is established with the minimum interference conflict, the highest demand satisfaction and the lowest neighbor frequency risk as the optimization objectives. A non-dominated ordering ant colony algorithm is proposed to solve the joint operation frequency planning problem. In the initial stage of the ant colony, a mountain-climbing algorithm with a greedy strategy is used to obtain the suboptimal solution set to improve the early convergence rate of the ant colony. In order to reduce the computational complexity of EMI analysis and speed up the process of the algorithm, the frequency equipment is grouped by community detection mechanism. At the same time, in each iteration of the algorithm, an improved scheduling operation is performed for the obtained frequency planning scheme, and parameters such as pheromone volatility coefficient are adjusted adaptively to improve the global optimization performance of the algorithm. Simulation results verify the effectiveness of the model, and prove the superiority of the algorithm in convergence, distribution and convergence speed by inverted generational distance and hyper volume.
Design of a dual-band bandpass filter with miniaturization and high selectivity
WANG Yuan, LIU Chao, NAN Jingchang, GAO Mingming
2022, 37(3): 443-448.   doi: 10.12265/j.cjors.2021138
Abstract(351) FullText HTML(110) PDF(33)
In order to meet the application requirements of C-band satellite communication system, a dual-band bandpass substrate integrated waveguide filter with miniaturization and high selectivity is proposed. The first passband of the filter is provided by an L-shaped resonant slot etched in the top layer of the quarter-mode substrate integrated waveguide cavity, and the second passband is provided by a new right/left-handed structure. The L-shaped resonant slot can act as a quarter-wavelength resonator to excite the fundamental mode in the cavity to produce a response at low frequencies; the new right/left-handed structure increases the fork-finger capacitance value compared with the conventional structure, then reduces the resonant frequency. Through simulation optimization and testing, the center frequencies of the dual-band bandpass filter are 3.9 GHz and 6.2 GHz with relative bandwidths of 3.3% and 2.1%, and the attenuation between the passbands is better than 70 dB, and three transmission zeros exist outside the passbands with good frequency selectivity. It is shown that the proposed filter has the characteristics of small size and high selectivity, which is very suitable for integration in the front-end system of satellite communication.
Analysis on the application of electromagnetic wave while drilling in the identification of minerals
LI Fukai, CHEN Jian, JI Yongli, YANG Zhiqiang, FAN Yehuo
2022, 37(3): 449-456.   doi: 10.12265/j.cjors.2021093
Abstract(168) FullText HTML(32) PDF(13)
Compared with mud pulse transmission, electromagnetic wave transmission while drilling has the advantages of not relying on drilling mud medium circulation and fast information transmission. In addition, electromagnetic wave transmission is sensitive to formation resistivity, which is convenient for timely discovery of mineral target layer. Based on the above characteristics, the electromagnetic wave transmission system while drilling has been more and more widely used in the exploitation of oil, natural gas and coal-bed methane (coal mine) in recent years. In this paper, the transmission of electromagnetic wave while drilling in the formation channel is analyzed by equivalent circuit method according to the propagation law of electromagnetic wave in the formation and the near-field radiation characteristics of extremely low frequency (ELF) electromagnetic wave which is different from the previous methods. In addition, according to the results of equivalent circuit analysis, the magnitude of the instantaneous change rate of the envelope of the electromagnetic wave signal amplitude received on the ground is used as the condition to judge the resistivity characteristics of the formation. The practical results of Qinshui coal seam exploration in Shanxi Province demonstrate that the method proposed in this paper has obvious timeliness in the exploration of coal and other mineral resources, and further proves that the electromagnetic wave information transmission system while drilling can also be used as an effective real-time logging system.
Three dimensional SAR imaging based on the focused electromagnetic vortex beam
GUO Shaoqing, HE Zi, CHEN Rushan
2022, 37(3): 457-464.   doi: 10.12265/j.cjors.2021070
Abstract(394) FullText HTML(108) PDF(39)
Synthetic aperture radar(SAR) is widely applied since it can break through the limitation of resolution by antenna aperture. In this paper, the focused electromagnetic(EM) vortex beam is applied to synthetic aperture radar to realize 3D imaging. By appropriately designing the imaging geometry, height resolution can be achieved with the use of the phase characteristics of EM vortex wave, and the relationship between height resolution and the number of orbital angular momentum(OAM) mode and radar parameters is derived. Considering the vortex phase term introduced in the echo signal, the improved back projection algorithm is applied to realize 3D imaging, and then sparse recovery algorithm is introduced to reduce the demand of the number of OAM mode. Simulation results indicate that the targets distributed at different heights can be accurately reconstructed, and high resolution is realized by sparse recovery method with few OAM modes. The method in this paper provides a certain reference for the research of new radar imaging system.
A deep learning algorithm with soft threshold for automatic modulation recognition
HE Rongrong, XU Yifan, LIU Jie, YAO Kailing
2022, 37(3): 465-470.   doi: 10.12265/j.cjors.2021052
Abstract(202) FullText HTML(224) PDF(49)
Due to the increasing complexity of electromagnetic spectrum environment, noise has significant influence on correct modulation recognition. In this paper, a deep learning model based on soft threshold is designed under the condition of low signal-noise ratio (SNR). The model is based on the convolutional neural network(CNN), and the soft threshold function is added. The IQ data is transformed into amplitude and phase information as the input of the model. The CNN is used to extract the features from the amplitude and phase data, and the soft threshold learning network can learn different thresholds aims to different features, which filters out the sample noise and improves the recognition rate under the condition of low SNR. Validation on the open source data set RML2016.10a shows that compared with other network structures, the model proposed in this paper has higher recognition rate and lower time complexity.
A novel method of antenna broadband radar cross section reduction by absorptive/transmissive metasurface
MA Yuhui, LIU Lu, JIA Shuaiyu, WANG Yihao, LI Yan
2022, 37(3): 471-477.   doi: 10.12265/j.cjors.2021116
Abstract(462) FullText HTML(142) PDF(207)
A metasurface with dual characteristics of absorbing/transmitting waves is designed and used for the superstrate of microstrip antennas to realize the wideband reduction of the radar cross section (RCS) of the antenna. In this paper, the metal unit of metamaterials absorber is replaced with tantalum nitride material to increase the absorbing bandwidth. At the same time, the combination of the absorbing material and the frequency selective surface is realizes. The superstrate has two completely different electromagnetic characteristics of absorbing/transmitting when the electromagnetic waves irradiate in different directions. The superstrate is placed above the antenna, and when the antenna is working, the electromagnetic waves radiated by the antenna can pass through the superstrate perfectly, so the radiation characteristics of the antenna will not be affected. When the electromagnetic waves irradiate the antenna, the broadband absorbing characteristics of the superstrate can minimize the RCS of the antenna. The results show that when the absorbing/transmitting metasurface designed in this paper is used as the antenna superstrate, the radiation characteristics of the antenna hardly change, and the maximum reduction of the monostatic RCS of the antenna can reach more than 20 dB, and the reduction bandwidth is 5−19 GHz. At the same time, the monostatic and bistatic RCS of the antenna have also been significantly reduced in a wide angle range.
Influence of ripple depth and ripple taper on bandwidth and center frequency shift operating at high frequency high order modes
DING Xueyong, WANG Liansheng
2022, 37(3): 478-483.   doi: 10.12265/j.cjors.2021136
Abstract(247) FullText HTML(78) PDF(19)
In order to provide a theoretical basis for the construction of a coaxial Bragg resonator with high-order single-mode operation at THz frequency. Based on the mode coupling theory, the influence of different ripple depths, different ripple taper shapes and different taper angles on the bandwidth and center frequency offset characteristics of the working mode and the competitive mode in the high-frequency high-order coupling mode of terahertz frequency are compared and studied. The results show that the bandwidth of the working mode and the competition mode becomes wider with the deepening of the ripple depth, but the center resonant frequency point almost does not shift, and the band gap overlap will worsen with the deepening of the ripple depth, which is not conducive to the mode selection; with the increase of the taper angle, the central frequency of the operating mode does not shift under the positive taper ripples structure, and the center frequency of the competition mode is close to the center frequency of the operating mode, which is not conducive to the suppression of the band gap overlap; with the increase of the taper angle, the center frequency of the competition mode of the negative taper ripples is far away from the operating mode, which is a good suppression of the band gap overlap; the positive taper ripples structure and negative taper ripples structure have little effect on the bandwidth. These characteristics are beneficial to expand the performance of the coaxial Bragg structure as a reflector and filter.
A miniaturized high isolation UWB-MIMO antenna
GAO Mingming, SONG Yang, NAN Jingchang, LI Chunchen
2022, 37(3): 484-490.   doi: 10.12265/j.cjors.2021129
Abstract(357) FullText HTML(131) PDF(51)
A compact, high performance, and novel-shaped ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with low mutual coupling is presented in this paper. The proposed antenna consists of two circular radiating elements with shared ground plane with an area of 30 mm×18 mm. F-shape stubs are introduced in the shared ground plane of the proposed antenna to produce high isolation between the MIMO antenna elements. The designed MIMO antenna has very low mutual coupling (S21 <−22 dB), low envelope correlation coefficient (ECC < 0.003), high diversity gain (DG > 9.98 dB), which is suitable for UWB-MIMO system applications.
Study on the Es responses of annular solar eclipse on June 21 of 2020
LIU Yao, ZHANG Yingqi, HU Yanli, ZHANG Yabin, DENG Zhongxin, XU Bin, XU Zhaohui, LI Jianghua
2022, 37(3): 491-496.   doi: 10.12265/j.cjors.2020278
Abstract(210) FullText HTML(104) PDF(14)
To study the evolution of irregularity of the ionosphere Es irregularities during the annular solar eclipse, we conducted a joint observation experiment using the VHF coherent scattering radar and a portable ionosonde system during the annular solar eclipse on 21 June, 2020. The results show that the variation of h′Es and foEs reduces first and then increases during the annular solar eclipse, which is similar to the effect of rapid sunrise and sunset on the irregularities in the ionosphere Es irregularities. The reason is that the solar activity as the radiation source experiences a rapid weakening and recovery process during the annular solar eclipse. The observation results of this experiment are of great significance to improve the formation mechanism of Es irregularities.
Optimization design of multi-band ring-focus antenna with elliptical beam
LIU Xinglong, DU Biao, ZHOU Jianzhai, XIE Lei
2022, 37(3): 497-504.   doi: 10.12265/j.cjors.2021284
Abstract(193) FullText HTML(52) PDF(12)
A synthetical optimization design method of elliptical beam antenna with ring-focus structure based on the cutting shaped ring focus antenna and non-uniform rational B-spline surface (NURBS) is proposed for the requirements of multi-band, high efficiency, low side-lobe, and low-profile antennas with small-aperture. Firstly, the one-dimensional aperture distribution is parameterized by spline function and the electrical performance of the cutting shaped ring-focus antenna is quickly optimized. Secondly, the main- and sub-reflectors of the optimized antenna are parameterized by NURBS surface, and a multi-objective optimization differential evolution algorithm is introduced to optimize the efficiency and first sidelobe of the ring-focus elliptical beam antenna. A 410 mm×720 mm ring-focus elliptical beam antenna is designed and fabricated. The operating frequency covers Ku/K/Ka tri-band. The total efficiency of the antenna is greater than 49%, the first sidelobe levels are lower than –14 dB, and the voltage standing wave ratio is less than 1.44∶1. The measured results are in good agreement with the full-wave simulation results, which verifies the effectiveness of the proposed design method.
Analysis on trans-horizon sea echoes of weather radar within an atmospheric duct process
ZHANG Han, WANG Hongguang, LI Jianru
2022, 37(3): 505-511.   doi: 10.12265/j.cjors.2021090
Abstract(228) FullText HTML(50) PDF(37)
Doppler radar data quality are seriously affected by trans-horizon ground and sea echoes in ducting conditions. Aimed at influence of the atmospheric duct on sea echoes, based on the weather radar and the sounding data from Qingdao station, one case of the atmospheric duct that took place on July 18−19 is analyzed. The sounding data indicates that a surface duct exists at 20: 00 July 18, and the radar data indicates that the trans-horizon sea echoes exist simultaneously. During this atmospheric duct process which lasted for about 24 hours, trans-horizon sea echoes received by the weather radar showed a general tendency of weak to strong, and to weak, and disappear in the end. The radar echoes have complex distribution and variation within this case. Range-depended ducting profiles are estimated from the radar echoes, the results of small difference show the effectively of the methods of calculating radar echoes and retrieving ducting profiles.
The design of 5.835 GHz microstrip array antenna
ZHU Furan, WU Aiting, ZHANG Pengquan, ZHANG Zhonghai, GUAN Boran
2022, 37(3): 512-517.   doi: 10.12265/j.cjors.2021066
Abstract(372) FullText HTML(138) PDF(42)
In order to reduce the adjacent channel interference and car following interference in the current electronic toll collection ETC system, a 5.835 GHz microstrip array antenna is designed. In this paper, the circular polarization of the antenna is realized by cutting the square patch angle. To improve the axial ratio bandwidth, four antenna elements are compensated by means of rotation and phase compensation. The improved antenna elements are used as the radiation elements of the microstrip array antenna. In terms of low sidelobe and high orientation, the paper designs a feed network with unequal amplitude feeding based on the Dolf-Chebyshev method of amplitude distribution. Through a large number of electromagnetic simulation, the optimal structure of the antenna is finally determined, and the physical processing and measurement are carried out. The measured results show that the impedance bandwidth is 5.67−5.88 GHz, the gain is greater than 15 dB, the axial ratio is less than 3 dB, and the E-plane half power lobe width is less than 12 degrees in the 5.7−5.9 GHz frequency band. The measured results are in good agreement with the simulation results. The antenna has the characteristics of low sidelobe, circular polarization and high orientation, which provides a novel antenna structure for the roadside unit array antenna of electronic toll collection system.
Preliminary study on loss of lock of satellite signal at the mid-latitude region in China
ZHAO Weihua, ZHANG Qinghe, WANG Cheng, WANG Yong, XING Zanyang
2022, 37(3): 518-525.   doi: 10.12265/j.cjors.2021076
Abstract(289) FullText HTML(76) PDF(28)
The phenomenon of loss of lock of satellite signal at the middle latitude region is firstly presented by using a ground-based GNSS ionospheric TEC and scintillation receiver (Weihai, China) 122.296°E, 36.866°N, during a period of 2018−2019. Based on our proposed criterion to filtering out loss of lock of satellite signal, a couple of classical loss of lock events have been shown. Moreover, the possible reasons to inducing them are then analyzed by using the global TEC data obtained from the madrigal database. The preliminary results suggest that the loss of lock phenomenon obtained by the ground-based receiver can still happen even during periods of low solar activities at middle latitudes of China. Furthermore, the duration of loss of lock cases varies from 1 minute to more than 10 minutes. Additionally, before and after the event of loss of lock, the signal-to-noise ratio (SNR) and scintillation indices are often strongly fluctuating. Regarding the possible generation reason, the rapid decrease of plasma density (or TEC) of the ionosphere are possibly associated with the loss of lock. Consequently, this study firstly investigates the loss of lock at middle-latitude regions in China through a ground-based GNSS receiver, extending our knowledge on this harmful phenomenon and suggesting the potential application value.
HEMP radiation effect test and electromagnetic damage assessment method of a certain radio equipment
LU Zhigang, CHEN Yuecheng, LIU Shuzhong, CUI Yanwu, WANG Tao
2022, 37(3): 526-534.   doi: 10.12265/j.cjors.2021071
Abstract(120) FullText HTML(73) PDF(22)
To test the survivability of radio equipment in the environment of high-altitude electromagnetic pulse (HEMP) and reduce the uncertainty of system electromagnetic pulse vulnerability assessment, the system level nuclear electromagnetic pulse irradiation test scheme and vulnerability test assessment process are designed, and the radio electromagnetic damage assessment algorithm based on fault tree model is established. Taking the electromagnetic vulnerability assessment of SG-7200 ultra short wave radio as an example, the threat level radiation test is carried out by using the electromagnetic damage assessment algorithm in this paper. The test results show that the radio frequency hopping phenomenon and communication failure occur in the 50 kV/m radiation test; in the fault tree model, according to the test data, the failure probability of the system is 78.83% in the 50 kV/m threat level radiation test.
Improved least-squares algorithm for TDOA/AOA-based localization
YAN Leibing, LU Yin, ZHANG Yerong
2016, 31(2): 394-400.   doi: 10.13443/j.cjors.2015041901
[Abstract](433) [FullText HTML](113) [PDF 798KB](238)
Current status and challenges of channel modeling for 5G wireless communication systems
PANG Lihua, ZHANG Yang, REN Guangliang, WANG Anyi, Li Jiandong
2017, 32(5): 487-497.   doi: 10.13443/j.cjors.2017091502
[Abstract](441) [FullText HTML](212) [PDF 15893KB](67)
Review of radio frequency fingerprinting identification
ZENG Yonghu, CHEN Xiang, LIN Yun, HAO Xiaojun, XU Xiong, WANG Liandong
2020, 35(3): 305-315.   doi: 10.13443/j.cjors.2019070501
[Abstract](311) [FullText HTML](77) [PDF 25896KB](83)
Research progress and prospect of atmospheric turbulence for wireless optical communication
KE Xizheng, WU Jiali, YANG Shangjun
2021, 36(3): 323-339.   doi: 10.12265/j.cjors.2020116
[Abstract](1241) [FullText HTML](467) [PDF 2286KB](151)
Path loss models of millimeter-wave channel in indoor environment at 28 GHz
LI Shuangde, LIU Yuanjian, LIN Leke
2017, 32(5): 602-611.   doi: 10.13443/j.cjors.2017091801
[Abstract](122) [FullText HTML](33) [PDF 22080KB](24)
Changes of propagation properties of orbital angular momentum for Laguerre-Gaussian beams in weak turbulent ocean
CHENG Mingjian, GUO Lixin, ZHANG Yixin
2016, 31(4): 737-742.   doi: 10.13443/j.cjors.2015121501
[Abstract](54) [FullText HTML](0) [PDF 707KB](185)
RSSI ranging method based on BP neural network model
FEI Yang, DU Qingzhi
2018, 33(2): 195-201.   doi: 10.13443/j.cjors.2017073001
[Abstract](169) [FullText HTML](77) [PDF 5013KB](38)
Design of a wideband 8-element MIMO antenna for 5G communication
LI Yixin, ZOU Huanqing, WANG Mingkai, YANG Guangli
2018, 33(4): 447-454.   doi: 10.13443/j.cjors.2018042702
[Abstract](532) [FullText HTML](187) [PDF 9302KB](56)
A design of compact ultrawideband MIMO antenna
WU Yanjie, LONG Yunliang
2016, 31(3): 421-425, 461.   doi: 10.13443/j.cjors.2015070401
[Abstract](524) [FullText HTML](84) [PDF 680KB](256)
The MoM-PO hybrid method for calculating the scattered field of multi-scale composite targets
WU Anwen, WU Yumao, YANG Yang, ZHANG Nan
2019, 34(1): 83-90.   doi: 10.13443/j.cjors.2018083101
[Abstract](103) [FullText HTML](59) [PDF 908KB](16)
Design of circularly-polarized microstrip antenna by SVM ensemble
TIAN Yubo, SUN Feiyan, REN Zuolin
2015, 30(6): 1086-1092.   doi: 10.13443/j.cjors.2014122901
[Abstract](384) [FullText HTML](275) [PDF 796KB](275)
A large deal of calculating data and complex structure is needed when design circularly-polarized microstrip antenna (CPMSA) with artificial neural network. To solve this problem, a synthesis model based on SVM ensemble (SVME) is proposed for the design of single-feed CPSMA with truncated corners. This method was based on the features of high fitting precision, simple structure, and the strong generalization ability of the support vector machine (SVM). The basic idea of the method was to optimally select differential SVMs to construct SVME with the aid of binary particle swarm optimization (BiPSO) algorithm. The model is validated by comparing its results with artificial neural network and a single SVM. Experiments show that the method is effective. It may improve the generalization ability of SVM and reduce the prediction error, and this model is superior to the problem of existing conclusions.
Two-bit coding-feeding metasurface with radiation and scattering manipulation
LI Sijia, HAN Bowen, HUANG Guoshuai, LI Zhuoyue, CAO Xiangyu
2021, 36(6): 925-931.   doi: 10.12265/j.cjors.2021111
[Abstract](1192) [FullText HTML](521) [PDF 18419KB](521)
Metasurface is a hotspot and frontier in the field of electromagnetic research, which can effectively regulate electromagnetic waves. Due to the increase of the number of units with different microstructures, the two-bit digital coding metasurface enhances the flexibility of scattering and radiation control, which makes it possible to achieve better stealth effect, wider bandwidth and multi-function. In this paper, the fractal magneto-electric dipole antenna structure and polarization metasurface unit are organically integrated to construct the unit of coding-feeding metasurface. Through the microstructure transformation and digital coding, a two-bit coding-feeding metasurface is proposed, and its topology is designed. The multi-functional characteristics of radiation and scattering manipulation are verified by simulation and experiment. The two-bit coding-feeding metasurface has potential application in radar cross section (RCS) reduction of antenna and wireless communication system in the future.

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