平直有耗地面上目標(biāo)地波散射FDTD近一遠場外推
AN FDTD NEAR TO FAR ZONE TRANSFORMATION FOR GROUND WAVE SCATTERING FROM OBJECTS ABOVE A FLAT EARTH
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摘要: 由平直有耗地面上垂直電偶極子產(chǎn)生地波場的解析解和互易原理,本文導(dǎo)出了用FDTD方法處理目標(biāo)地波散射問題時的近一遠場外推公式。在數(shù)值結(jié)果驗證了該公式的正確性之后,對海上一金屬半球的地波散射場進行了求解,并以此與李清亮等(1997)提出的工程應(yīng)用方法相對比,考察了工程應(yīng)用方法的適用性。
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關(guān)鍵詞:
- 地波散射; FDTD方法; 近-遠場外推
Abstract: A scheme of FDTD near to far zone transformation for ground wave scattering from objects above a flat earth is presented in this paper. With the equivalent principle, the equivalent electric and magnetic currents can be obtained from FDTD near field output boundaries. The fields radiated by these currents in the presence of a flat earth are then calculated using the reciprocity theorem and the known lateral wave formula of a vertical dipole(King, et al. 1992). Numerical results show excellent agreement between this scheme and analytical method. The feasibility of another approximation approach (Q.L.Li, et al. 1997) is also tested by this scheme. -
Li Qingliang, Ge Debiao, et al. Ground wave scattering from a ship on the sea. Proc. of 97 Int. Symp. on Radio Popagat., Qingdao, China, Aug. 1997, 134-136.[2]King R W P, Owens M, Wu T T. Lateral Electromagnetic Wave. New York: Springer-verlay, 1992,51-86.[3]Wong P B, Tyler G L, Baron J E, Simpson R A. A three-wave FDTD approach to surface scattering with application to remote sensing of geophysical surface. IEEE Trans. on Antennas and Propagt., 1996, AP-44(4): 504-514.[4]Demarest K, Huang Z B, Plumb R. An FDTD near-to far-zone transformation for scatterers buried in stratified ground. IEEE Trans. on Antennas and Propagt., 1996, AP-44(8): 1150-1157.[5]Harrington R F. Time-Harmonic Electromagnetic Fields. New York: McGraw-Hill, 1961, Chapter 3.[6]吳良超,汪茂光.復(fù)宗量菲涅爾函數(shù)的計算及其性質(zhì).電子科學(xué)學(xué)刊,1996, 16(6): 614-621.[7]Yee K S. Numerical solution of initial boundary value problems involving Maxwells equations in isotropic media. IEEE Trans. on Antennas and Propagt., 1966, AP-14(5): 302-306. -
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