The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting pla...The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting platforms to realize fast, accurate solutions. Wire, surface and junction basis functions are used to model the current distribution on the object. Application of MLFMA reduces memory requirement and computing time compared to conventional methods, such as method of moment (MOM), especially for the antenna on a large-sized platform. Generalized minimal residual (GMRES) solver with incomplete LU factorization preconditioner using a dual dropping strategy (ILUT) is applied to reduce the iterative number. Several typical numerical examples are presented to validate this algorithm and show the accuracy and computational efficiency.展开更多
An efficient analyzing approach is presented for large slotted-waveguide antenna arrays by using hybrid finite element-boundary integral-multilevel fast multipole algorithm（FE-BI-MLFMA）in this paper.A simple computa...An efficient analyzing approach is presented for large slotted-waveguide antenna arrays by using hybrid finite element-boundary integral-multilevel fast multipole algorithm（FE-BI-MLFMA）in this paper.A simple computation model for slotted-waveguide antenna is presented by using thin current probe excitation and perfectly matched layer（PML）absorber.Since each slotted-waveguide antenna can be considered as a single sub-domain,the domain decomposition algorithm（DDA）can be applied to FE-BI-MLFMA to greatly reduce the computation resources and achieve high efficiency.This DDA-FE-BI-MLMFA is parallelized to further strength its capability.The comparisons of the computed radiation patterns with measured data and results from the commercial software show that our method has good accuracy for slottedwaveguide array.Then the influence of mutual coupling between adjacent slotted-waveguides is studied.To demonstrate capability of the presented method,a carefully designed large X-band slotted-waveguide antenna array containing eighteen waveguides with Taylor amplitude and inverse phase excitation distribution are analyzed in the paper.展开更多
It is a major challenge for the airframe-inlet design of modern combat aircrafts,as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very complex.In this study,an aerodynamic/stealth ...It is a major challenge for the airframe-inlet design of modern combat aircrafts,as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very complex.In this study,an aerodynamic/stealth optimization design method for an S-duct inlet is proposed.The upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow separation.The multilevel fast multipole algorithm(MLFMA)is utilized for the stealth adjoint equation.A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth characteristics.Both the aerodynamic and stealth characteristics of the inlet are effectively improved.Finally,the optimization results are analyzed,and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and crosssectional area.The S-duct is smoothed,and the cross-sectional area is increased to improve the aerodynamic characteristics,while it is completely opposite for the stealth design.The radar cross section(RCS)is reduced by phase cancelation for low frequency conditions.The method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system.展开更多
基金This project was supported by the National Natural Science Foundation of China (60431010).
文摘The electric field integral equation (EFIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze the radiation and impedance properties of wire antennas mounted on complex conducting platforms to realize fast, accurate solutions. Wire, surface and junction basis functions are used to model the current distribution on the object. Application of MLFMA reduces memory requirement and computing time compared to conventional methods, such as method of moment (MOM), especially for the antenna on a large-sized platform. Generalized minimal residual (GMRES) solver with incomplete LU factorization preconditioner using a dual dropping strategy (ILUT) is applied to reduce the iterative number. Several typical numerical examples are presented to validate this algorithm and show the accuracy and computational efficiency.
基金Supported by the National Key Basic Research Program(973 Program)(2012CB720702,61320602)the 111 Project of China(B14010)the National Natural Science Foundation of China(61371002)
文摘An efficient analyzing approach is presented for large slotted-waveguide antenna arrays by using hybrid finite element-boundary integral-multilevel fast multipole algorithm（FE-BI-MLFMA）in this paper.A simple computation model for slotted-waveguide antenna is presented by using thin current probe excitation and perfectly matched layer（PML）absorber.Since each slotted-waveguide antenna can be considered as a single sub-domain,the domain decomposition algorithm（DDA）can be applied to FE-BI-MLFMA to greatly reduce the computation resources and achieve high efficiency.This DDA-FE-BI-MLMFA is parallelized to further strength its capability.The comparisons of the computed radiation patterns with measured data and results from the commercial software show that our method has good accuracy for slottedwaveguide array.Then the influence of mutual coupling between adjacent slotted-waveguides is studied.To demonstrate capability of the presented method,a carefully designed large X-band slotted-waveguide antenna array containing eighteen waveguides with Taylor amplitude and inverse phase excitation distribution are analyzed in the paper.
文摘It is a major challenge for the airframe-inlet design of modern combat aircrafts,as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very complex.In this study,an aerodynamic/stealth optimization design method for an S-duct inlet is proposed.The upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow separation.The multilevel fast multipole algorithm(MLFMA)is utilized for the stealth adjoint equation.A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth characteristics.Both the aerodynamic and stealth characteristics of the inlet are effectively improved.Finally,the optimization results are analyzed,and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and crosssectional area.The S-duct is smoothed,and the cross-sectional area is increased to improve the aerodynamic characteristics,while it is completely opposite for the stealth design.The radar cross section(RCS)is reduced by phase cancelation for low frequency conditions.The method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system.
