Passive jamming is believed to have very good potential in countermeasure community.In this paper,a passive angular blinking jamming method based on electronically controlled corner reflectors is proposed.The amplitud...Passive jamming is believed to have very good potential in countermeasure community.In this paper,a passive angular blinking jamming method based on electronically controlled corner reflectors is proposed.The amplitude of the incident wave can be modulated by switching the corner reflector between the penetration state and the reflection state,and the ensemble of multiple corner reflectors with towing rope can result in complex angle decoying effects.Dependency of the decoying effect on corner reflectors’radar cross section and positions are analyzed and simulated.Results show that the angle measured by a monopulse radar can be significantly interfered by this method while the automatic tracking is employed.展开更多
In order to improve the underwater acoustic target strength of comer reflectors,according to the principle of acoustic impedance mismatch of the boundary layer,the method of using air cavity to increase the underwater...In order to improve the underwater acoustic target strength of comer reflectors,according to the principle of acoustic impedance mismatch of the boundary layer,the method of using air cavity to increase the underwater acoustic target strength of corner reflectors is proposed.The acoustic reflection coefficients of underwater air layer and single layer metal sheet are calculated and compared.The results show that the reflection coefficient of single layer metal sheet is greatly affected by frequency and incidence angle,and the reflection coefficient of air layer in water is large and little affected by frequency and incidence angle.On this basis,a new kind of airfilled cavity corner reflector is designed.The acoustic scattering characteristics of underwater airfilled cavity comer reflector are calculated cumulatively,and the results are compared with the monolayer metal sheet corner reflector.The simulation results show that the acoustic reflection effect of the airfilled cavity corner reflector is better.In order to verify the correctness of the method,the test was carried out in the silencing tank.The experimental results show that the simulation results are in good agreement with the experimental results,and the airfilled cavity can improve on acoustic reflection performance of the underwater corner reflector.展开更多
A gradient-based optimization method for producing a contoured beam by using a single-fed reflector antenna is presented. First, a quick and accurate pattern approximation formula based on physical optics(PO) is adopt...A gradient-based optimization method for producing a contoured beam by using a single-fed reflector antenna is presented. First, a quick and accurate pattern approximation formula based on physical optics(PO) is adopted to calculate the gradients of the directivity with respect to reflector's nodal displacements. Because the approximation formula is a linear function of nodal displacements, the gradient can be easily derived. Then, the method of the steepest descent is adopted, and an optimization iteration procedure is proposed. The iteration procedure includes two loops: an inner loop and an outer loop. In the inner loop, the gradient and pattern are calculated by matrix operation, which is very fast by using the pre-calculated data in the outer loop. In the outer loop, the ideal terms used in the inner loop to calculate the gradient and pattern are updated, and the real pattern is calculated by the PO method. Due to the high approximation accuracy, when the outer loop is performed once, the inner loop can be performed many times, which will save much time because the integration is replaced by matrix operation. In the end, a contoured beam covering the continental United States(CONUS) is designed, and simulation results show the effectiveness of the proposed algorithm.展开更多
Based on the works of Greve and Rahmat-Samii, theelectromagnetic （EM） performance of the reflector antenna withnon-uniform surface errors along radius is further addressed. Amathematical model is developed to descri...Based on the works of Greve and Rahmat-Samii, theelectromagnetic （EM） performance of the reflector antenna withnon-uniform surface errors along radius is further addressed. Amathematical model is developed to describe the weighting functionfor the non-uniform surface errors along radius. Then, somediscussions on the peak gain loss （PGL） and the first sidelobelevel increase （SLLI） caused by the non-uniform surface errors arepresented and several significant radiation characteristics of thereflector with non-uniform errors are pointed out. Last, based onthe proposed model, the weighted root mean square （RMS） valueof the surface errors is produced to evaluate the EM performanceand several representative cases with different non-uniform errorsare presented with good results. Results show that the weightedRMS value should be taken into account for a better quality evaluationof the reflector surface.展开更多
This paper discusses the basic principle and design m ethod for light distribution of car lamp, introduces an important development: h igh efficient and flexible car lamp with reflecting light distribution-segmente d ...This paper discusses the basic principle and design m ethod for light distribution of car lamp, introduces an important development: h igh efficient and flexible car lamp with reflecting light distribution-segmente d reflector (multi-patch) car lamp, and puts out a design method for segmented reflector based on error analysis. Unlike classical car lamp with refractive lig ht distribution, the method of reflecting light distribution gives car lamp desi gn more flexibility. In the case of guarantying the lightness of car lamp and sa tisfying the standard demand for the light distribution, the design of the exter ior of the car lamp has more freedom. The high gradient of car lamp is more suit able for the demand of streamline of the car exterior. The shape of segmented re flector obtained by theory calculating of car lamp reflecting light distribution is only an ideal shape, which usually has considerable differences with the fin al shape and will influences light distribution. There exist difference between the calculated reflector and manufactured reflector. Owing to light reflecting c haracter, the small diversification of the reflector will reduce the big diver sification of the light distribution shape on light distribution screen in 25 -meter place, so light distribution quality can’t be ensured. To ensure the re flector by light distribution calculation accordance to reflector by practical m anufacture, the error effect of surface shape must be reasonably considered name ly the error effect of manufacture tache. The paper establishes error-analyzing model for segmented reflector according to the analysis of error of making proc ess for segmented reflector. Based on this error-analyzing model and by use of the analyzing software developed for segmented reflector light distribution, it could reasonably consider reflector errors made by manufacturing, such as reflec tor surface spray-painting and plating aluminum, which could give out shapes of reflector patches for segmented reflector well and truly, and direct the plan o f making process efficiently. The method put by the paper has successfully appli ed to develop segmented reflector lamp for several type cars and obtained good e ffect for the factory.展开更多
An user-oriented computer software consisting of three modeling codes, named DRAD, DRAA and FDPAT, is introduced. It can be used to design three types of Cassegrain system: classical, with shaped subreflector and with...An user-oriented computer software consisting of three modeling codes, named DRAD, DRAA and FDPAT, is introduced. It can be used to design three types of Cassegrain system: classical, with shaped subreflector and with dual shaped reflectors, and to analyse radiation patterns for the antennas. Several mathematical models and numerical techniques are presented.展开更多
A design method of a new shaped spherical reflector antenna with a horn feed for wide-angle scanning is presented,in which the horn's phase center need not be found out and its optimal position can be determined.I...A design method of a new shaped spherical reflector antenna with a horn feed for wide-angle scanning is presented,in which the horn's phase center need not be found out and its optimal position can be determined.It is found from numerical calculation that the shaped spherical reflector antenna has better electrical performance than that of the spherical reflector antenna,at the maximum gain value under the conditions of the same feed and reflector aperture,and can be used as a wide angle searching antenna.展开更多
针对现有任意反射面速度干涉仪(velocity interferometer system for any reflector,VISAR)装置中依靠人工准直光路的现状,同时为满足未来对远程自动化控制的需求,提出一种新的光路自动准直的方法。该方法通过互补金属氧化物半导体(comp...针对现有任意反射面速度干涉仪(velocity interferometer system for any reflector,VISAR)装置中依靠人工准直光路的现状,同时为满足未来对远程自动化控制的需求,提出一种新的光路自动准直的方法。该方法通过互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)间接测量并以光斑的像素偏差为系统输入,通过系数矩阵转换和离散模糊反馈控制方法快速消除误差。基于Windows的控制和自动化技术(the Windows control and automation technology,TwinCAT)中视觉和运动等模块,将各模块分别运行在不同的实时内核中,消除了视觉与运动控制模块间的通信环节,实现了快速实时的闭环控制。经过冲击波速度测量实验验证,该系统实现了远程“一键式”自动准直,可将准直时间缩短到2 s,准直精度为4.5μm,解决了现有装置人工调节效率不高的问题,提高了系统的精度和稳定性。展开更多
基金supported by the Equipment Pre-research Project(GK202002A020068)。
文摘Passive jamming is believed to have very good potential in countermeasure community.In this paper,a passive angular blinking jamming method based on electronically controlled corner reflectors is proposed.The amplitude of the incident wave can be modulated by switching the corner reflector between the penetration state and the reflection state,and the ensemble of multiple corner reflectors with towing rope can result in complex angle decoying effects.Dependency of the decoying effect on corner reflectors’radar cross section and positions are analyzed and simulated.Results show that the angle measured by a monopulse radar can be significantly interfered by this method while the automatic tracking is employed.
文摘In order to improve the underwater acoustic target strength of comer reflectors,according to the principle of acoustic impedance mismatch of the boundary layer,the method of using air cavity to increase the underwater acoustic target strength of corner reflectors is proposed.The acoustic reflection coefficients of underwater air layer and single layer metal sheet are calculated and compared.The results show that the reflection coefficient of single layer metal sheet is greatly affected by frequency and incidence angle,and the reflection coefficient of air layer in water is large and little affected by frequency and incidence angle.On this basis,a new kind of airfilled cavity corner reflector is designed.The acoustic scattering characteristics of underwater airfilled cavity comer reflector are calculated cumulatively,and the results are compared with the monolayer metal sheet corner reflector.The simulation results show that the acoustic reflection effect of the airfilled cavity corner reflector is better.In order to verify the correctness of the method,the test was carried out in the silencing tank.The experimental results show that the simulation results are in good agreement with the experimental results,and the airfilled cavity can improve on acoustic reflection performance of the underwater corner reflector.
基金supported by the National Natural Science Foundation of China(51805399)the Fundamental Research Funds for the Central Universities(JB180403)+2 种基金the Chinese Academy of Sciences(CAS)"Light of West China" Program(2017-XBQNXZ-B-024)the National Basic Research Program of China(973 Program)(2015CB857100)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the CAS
文摘A gradient-based optimization method for producing a contoured beam by using a single-fed reflector antenna is presented. First, a quick and accurate pattern approximation formula based on physical optics(PO) is adopted to calculate the gradients of the directivity with respect to reflector's nodal displacements. Because the approximation formula is a linear function of nodal displacements, the gradient can be easily derived. Then, the method of the steepest descent is adopted, and an optimization iteration procedure is proposed. The iteration procedure includes two loops: an inner loop and an outer loop. In the inner loop, the gradient and pattern are calculated by matrix operation, which is very fast by using the pre-calculated data in the outer loop. In the outer loop, the ideal terms used in the inner loop to calculate the gradient and pattern are updated, and the real pattern is calculated by the PO method. Due to the high approximation accuracy, when the outer loop is performed once, the inner loop can be performed many times, which will save much time because the integration is replaced by matrix operation. In the end, a contoured beam covering the continental United States(CONUS) is designed, and simulation results show the effectiveness of the proposed algorithm.
基金supported by the National Basic Research Program of China(973 Program)(2015CB857100)the Foundation for Key Laboratory of Xinjiang Uygur Autonomous Region(2014KL012)+2 种基金the National Natural Science Foundation of China(514906605147534951522507)
文摘Based on the works of Greve and Rahmat-Samii, theelectromagnetic （EM） performance of the reflector antenna withnon-uniform surface errors along radius is further addressed. Amathematical model is developed to describe the weighting functionfor the non-uniform surface errors along radius. Then, somediscussions on the peak gain loss （PGL） and the first sidelobelevel increase （SLLI） caused by the non-uniform surface errors arepresented and several significant radiation characteristics of thereflector with non-uniform errors are pointed out. Last, based onthe proposed model, the weighted root mean square （RMS） valueof the surface errors is produced to evaluate the EM performanceand several representative cases with different non-uniform errorsare presented with good results. Results show that the weightedRMS value should be taken into account for a better quality evaluationof the reflector surface.
文摘This paper discusses the basic principle and design m ethod for light distribution of car lamp, introduces an important development: h igh efficient and flexible car lamp with reflecting light distribution-segmente d reflector (multi-patch) car lamp, and puts out a design method for segmented reflector based on error analysis. Unlike classical car lamp with refractive lig ht distribution, the method of reflecting light distribution gives car lamp desi gn more flexibility. In the case of guarantying the lightness of car lamp and sa tisfying the standard demand for the light distribution, the design of the exter ior of the car lamp has more freedom. The high gradient of car lamp is more suit able for the demand of streamline of the car exterior. The shape of segmented re flector obtained by theory calculating of car lamp reflecting light distribution is only an ideal shape, which usually has considerable differences with the fin al shape and will influences light distribution. There exist difference between the calculated reflector and manufactured reflector. Owing to light reflecting c haracter, the small diversification of the reflector will reduce the big diver sification of the light distribution shape on light distribution screen in 25 -meter place, so light distribution quality can’t be ensured. To ensure the re flector by light distribution calculation accordance to reflector by practical m anufacture, the error effect of surface shape must be reasonably considered name ly the error effect of manufacture tache. The paper establishes error-analyzing model for segmented reflector according to the analysis of error of making proc ess for segmented reflector. Based on this error-analyzing model and by use of the analyzing software developed for segmented reflector light distribution, it could reasonably consider reflector errors made by manufacturing, such as reflec tor surface spray-painting and plating aluminum, which could give out shapes of reflector patches for segmented reflector well and truly, and direct the plan o f making process efficiently. The method put by the paper has successfully appli ed to develop segmented reflector lamp for several type cars and obtained good e ffect for the factory.
文摘An user-oriented computer software consisting of three modeling codes, named DRAD, DRAA and FDPAT, is introduced. It can be used to design three types of Cassegrain system: classical, with shaped subreflector and with dual shaped reflectors, and to analyse radiation patterns for the antennas. Several mathematical models and numerical techniques are presented.
文摘A design method of a new shaped spherical reflector antenna with a horn feed for wide-angle scanning is presented,in which the horn's phase center need not be found out and its optimal position can be determined.It is found from numerical calculation that the shaped spherical reflector antenna has better electrical performance than that of the spherical reflector antenna,at the maximum gain value under the conditions of the same feed and reflector aperture,and can be used as a wide angle searching antenna.
文摘针对现有任意反射面速度干涉仪(velocity interferometer system for any reflector,VISAR)装置中依靠人工准直光路的现状,同时为满足未来对远程自动化控制的需求,提出一种新的光路自动准直的方法。该方法通过互补金属氧化物半导体(complementary metal oxide semiconductor,CMOS)间接测量并以光斑的像素偏差为系统输入,通过系数矩阵转换和离散模糊反馈控制方法快速消除误差。基于Windows的控制和自动化技术(the Windows control and automation technology,TwinCAT)中视觉和运动等模块,将各模块分别运行在不同的实时内核中,消除了视觉与运动控制模块间的通信环节,实现了快速实时的闭环控制。经过冲击波速度测量实验验证,该系统实现了远程“一键式”自动准直,可将准直时间缩短到2 s,准直精度为4.5μm,解决了现有装置人工调节效率不高的问题,提高了系统的精度和稳定性。
