半空间环境下跨界金属目标电磁散射快速分析研究
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摘要
通过对半空间分界面进行截断,半空间环境下目标的散射问题可以等效为自由空间中目标与背景构成的复合介质体的散射问题。不同于传统的半空间散射问题分析方法,该文使用自由空间格林函数,从而避免复杂耗时的半空间格林函数的计算,特别是当目标靠近或横跨分界面时。根据自由空间格林函数的特性,该方法可以有效地利用多层快速多级子方法进行加速处理,不仅解决了传统的半空间问题中缺乏有效的快速方法的问题,而且改善了由截断半空间分界面而引入的额外未知量问题。通过对跨界舰船的数值分析,验证了该方法的准确性和有效性。另外,从能量守恒的角度出发,提出了透射深度的概念,为跨界目标处于下半空间部分的截断问题提供了依据。
By truncating the half-space interface, the analysis of scattering from a PEC body straddling a half-space interface can be cast into that of a composite dielectric object in the free space. Different from the traditional half-space method, the Green's function of the free space has been used and the extremely time-consuming numerical evaluations of the half-space Green's functions can be totally avoided, which involve the complicated Sommerfeld integrals and is especially difficult to evaluate when the objects get close to or straddle the interface. Moreover, fast algorithms such as the MLFMA can be incorporated easily without any restrictions, effectively compensating the cost due to the introduction of additional unknowns by the truncation. Scattering from a PEC ship straddling the interface has been studied to demonstrate the accuracy and efficiency of the proposed method. Moreover, based on the principle of conservation of energy, the concept of transmission depth has been defined firstly, providing the basis for cutting off the buried part of the objects straddling the half-space interface.
By truncating the half-space interface, the analysis of scattering from a PEC body straddling a half-space interface can be cast into that of a composite dielectric object in the free space. Different from the traditional half-space method, the Green's function of the free space has been used and the extremely time-consuming numerical evaluations of the half-space Green's functions can be totally avoided, which involve the complicated Sommerfeld integrals and is especially difficult to evaluate when the objects get close to or straddle the interface. Moreover, fast algorithms such as the MLFMA can be incorporated easily without any restrictions, effectively compensating the cost due to the introduction of additional unknowns by the truncation. Scattering from a PEC ship straddling the interface has been studied to demonstrate the accuracy and efficiency of the proposed method. Moreover, based on the principle of conservation of energy, the concept of transmission depth has been defined firstly, providing the basis for cutting off the buried part of the objects straddling the half-space interface.
引文
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[2]CHEN Ying-ping,CHEW W C,JIANG Li-jun.A new Green’s function formulation for modeling homogeneous objects in layered medium[J].IEEE Trans AP,2012,60(10):4766-4776.
[3]CHEW W C,Waves and fields in inhomogeneous media[M].New York:Van Nostrand Reinhold,1990.
[4]YANG J J,CHOW Y L,FANG D G.Discrete complex images of a three-dimensional dipole above and within a lossy ground[J].Microw AP IEE Proc H,1991,138(4):319-326.
[5]CHEN Ying-ping,XIONG J L,CHEW W C.A mixed-form thin-stratified medium fast-multipole algorithm for both low and mid-frequency problems[J].IEEE Trans AP,2011,59(6):2341-2349.
[6]GENG N,SULLIVAN A,CARIN L.Multilevel fast-multipole algorithm for scattering from conducting targets above or embedded in a lossy half space[J].IEEE Trans Geosci Remote Sens,2000,38(4):1561-1573.
[7]LUO Wan,NIE Zai-ping,CHEN Ying-ping.Fast analysis of electromagnetic scattering from three-dimensional objects straddling the interface of a half space[J].IEEE Geosci Remote Sens Lett,2014,11(7):1205-1209.