【摘要】：隨著海洋資源的開發(fā)和其戰(zhàn)略位置的重要性,對粗糙海面的電磁散射特性研究越來越受到各國重視。由于海面環(huán)境的復(fù)雜多變,海雜波對于雷達(dá)目標(biāo)探測,截獲和制導(dǎo)等等帶來干擾,所以分析不同海態(tài)海況不同條件下的海面電磁散射刻不容緩。本論文就快速多極子方法(FMM)和基于矩量法(MOM)的并行計算方法在低掠角下的破碎波電磁散射應(yīng)用中展開理論研究。論文主要工作如下:1.對粗糙面電磁散射基本理論進(jìn)行了簡述,包括雷達(dá)方程,海水介電常數(shù)的雙Debye模型,入射錐形波各參數(shù)的選擇,使用蒙特卡羅方法模擬生成了PM海譜,結(jié)合LONGTANK破波模型,建立了破碎波的幾何模型。2.簡單介紹了矩量法(MOM)和快速多極子方法(FMM)的基本原理,進(jìn)而推導(dǎo)了快速多極子方法的計算公式,研究了低掠角下快速多極子方法在粗糙海面電磁散射中的應(yīng)用,在不同極化,不同入射角度,不同頻率,不同風(fēng)速下的導(dǎo)體海面和介質(zhì)海面的電磁散射系數(shù)隨散射角度的變化。3.將基于MPI的并行計算和基于OpenMP的并行計算引入到粗糙海面的電磁散射快速算法當(dāng)中,給出了并行算法的具體加速過程,并將兩種并行算法計算結(jié)果和時間與矩量法或是快速多極子方法進(jìn)行了對比,驗證了并行算法的高效精確,突出了并行算法在求解矩陣當(dāng)中的優(yōu)勢。4.將快速多極子方法和并行計算方法應(yīng)用到破碎波的電磁散射計算當(dāng)中,分析討論了破碎波生成過程當(dāng)中的不同時期的電磁散射狀況,依據(jù)其后向電磁散射隨入射角的變化,在破碎波形成前期,未顯現(xiàn)多徑效應(yīng),VV極化大于HH極化,在破碎波生成中期,開始出現(xiàn)浪尖,VV極化減弱而HH極化增強,隨著海面演變,在破碎波形成后期,海面出現(xiàn)完整卷浪,明顯的海尖峰現(xiàn)象,HH極化和VV極化差異變大
[Abstract]:With the development of marine resources and the importance of their strategic position, more and more attention has been paid to the electromagnetic scattering characteristics of rough sea. Due to the complexity of sea environment and the interference of sea clutter to radar target detection, interception and guidance, it is urgent to analyze the electromagnetic scattering of sea surface under different sea conditions. In this paper, the fast multipole method (FMM) and the parallel computing method based on the method of moments (MOM) are studied in the applications of electromagnetic scattering of broken waves at low grazing angles. The main work of this paper is as follows: 1. The basic theory of electromagnetic scattering from rough surface is briefly described, including the radar equation, the double Debye model of the dielectric constant of seawater, and the selection of parameters of the incident conical wave. The PM sea spectrum is simulated by Monte Carlo method and combined with the LONGTANK wave breaking model. The geometric model of broken wave is established. 2. In this paper, the basic principles of (MOM) and (FMM) are introduced, and the formula of fast multipole method is deduced. The application of fast multipole method in electromagnetic scattering from rough sea surface at low grazing angle is studied. The variation of electromagnetic scattering coefficient of conducting sea surface and medium sea surface with different incident angle, frequency, wind speed and scattering angle. 3. The parallel computation based on MPI and the parallel computation based on OpenMP are introduced into the fast electromagnetic scattering algorithm of rough sea surface, and the concrete acceleration process of the parallel algorithm is given. The results and time of the two parallel algorithms are compared with the method of moments or the fast multipole method, which verifies the high efficiency and accuracy of the parallel algorithm, and highlights the advantages of the parallel algorithm in solving the matrix. 4. The fast multipole method and the parallel calculation method are applied to the electromagnetic scattering calculation of broken waves. The electromagnetic scattering conditions in different periods during the process of breaking wave generation are analyzed and discussed. According to the variation of the backscatter with the incident angle, In the early stage of breaking wave formation, there was no multipath effect. VV polarization was larger than HH polarization. In the middle stage of breaking wave formation, wave tip began to appear. VV polarization weakened and HH polarization increased. With the evolution of sea surface, the whole wave appeared in the later stage of breaking wave formation. The obvious sea spike phenomenon, the difference between HH polarization and VV polarization becomes bigger.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN011

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