【摘要】：為了滿(mǎn)足通信、雷達(dá)和導(dǎo)航應(yīng)用的需求,現(xiàn)代大型艦船平臺(tái)上通常安裝著各種電子系統(tǒng)。這些電子系統(tǒng)的近場(chǎng)互耦會(huì)導(dǎo)致復(fù)雜的電磁環(huán)境效應(yīng),使得系統(tǒng)整體性能變差。另外,這些電子系統(tǒng)和艦船平臺(tái)對(duì)外來(lái)電磁干擾(Electromagnetic Interference,EMI)非常敏感,嚴(yán)重時(shí)會(huì)導(dǎo)致系統(tǒng)失效。解決這些電大尺寸、多尺度的平臺(tái)級(jí)電磁兼容(Electromagnetic Compatibility,EMC)問(wèn)題需要高效、精確的數(shù)值計(jì)算方法。時(shí)域有限差分算法(Finite-Difference Time-Domain,FDTD)已經(jīng)被大量應(yīng)用于解決這些問(wèn)題,然而由于FDTD的時(shí)間步長(zhǎng)受限于空間網(wǎng)格大小,傳統(tǒng)的FDTD方法在求解這類(lèi)問(wèn)題時(shí)計(jì)算效率受到嚴(yán)重限制。本文針對(duì)大型艦船平臺(tái)上的電磁兼容問(wèn)題,拓展了單步無(wú)條件穩(wěn)定時(shí)域有限差分算法(Leapfrog Alternately-Direction-Implicit FDTD,ADI-FDTD),應(yīng)用于艦船平臺(tái)上細(xì)線天線的精確仿真。本論文主要內(nèi)容和創(chuàng)新點(diǎn)如下:(1)介紹了傳統(tǒng)FDTD和隱式FDTD算法中效率最高的Leapfrog ADI-FDTD的基本迭代方程和Yee網(wǎng)格剖分,并分析了算法的數(shù)值色散特性和穩(wěn)定性條件。其次介紹了卷積完美匹配層(Convolutional Perfectly Matched Layer,CPML)和引入各種不同激勵(lì)源的方法。最后介紹了 FDTD中經(jīng)典的細(xì)導(dǎo)線模型。(2)將FDTD中經(jīng)典的細(xì)導(dǎo)線算法拓展到Leapfrog ADI-FDTD中,適用于仿真大型艦船平臺(tái)上的單極子細(xì)線天線�；赩onNeumann方法和大量數(shù)值實(shí)驗(yàn),半解析地證明了該算法的無(wú)條件穩(wěn)定性。將該算法應(yīng)用于仿真大型艦船平臺(tái)上的電磁兼容問(wèn)題,包括計(jì)算天線之間近場(chǎng)耦合效應(yīng)(S參數(shù))和天線遠(yuǎn)場(chǎng)輻射方向圖,以及有外來(lái)平面波輻照下天線端口感應(yīng)的電壓和艦船平臺(tái)表面電流密度分布。(3)設(shè)計(jì)了一種雙頻雙圓極化偏心圓環(huán)微帶天線,對(duì)天線的工作機(jī)理進(jìn)行了深入探究,并研究了不同結(jié)構(gòu)參數(shù)對(duì)天線性能的影響。提出了一個(gè)集總元件等效電路以深入理解天線的工作機(jī)理,并給出一組經(jīng)驗(yàn)公式和設(shè)計(jì)指導(dǎo)以簡(jiǎn)化設(shè)計(jì)流程。最后制作了天線實(shí)物并進(jìn)行實(shí)驗(yàn)測(cè)量,結(jié)果與仿真吻合較好。
[Abstract]:In order to meet the needs of communication, radar and navigation applications, modern large ship platforms are usually equipped with various electronic systems. The near field mutual coupling of these electronic systems will lead to complex electromagnetic environmental effects, which makes the overall performance of the system worse. In addition, these electronic systems and ship platforms are sensitive to external electromagnetic interference (Electromagnetic Interference,EMI), which can lead to system failure. Solving these electrically large scale and multi-scale platform-level electromagnetic compatibility (Electromagnetic Compatibility,EMC) problems requires efficient and accurate numerical methods. Finite-Difference Time-Domain (Finite-Difference Time-Domain,FDTD) algorithm has been widely used to solve these problems. However, the time step size of FDTD is limited by the size of space mesh. The computational efficiency of the traditional FDTD method is severely limited in solving this kind of problems. In order to solve the electromagnetic compatibility problem on large ship platforms, this paper extends the single step unconditionally stable finite difference time-domain (Leapfrog Alternately-Direction-Implicit FDTD,ADI-FDTD) algorithm, which is applied to the precise simulation of thin wire antennas on ship platforms. The main contents and innovations of this thesis are as follows: (1) the basic iterative equations and Yee mesh generation of the most efficient Leapfrog ADI-FDTD in the traditional FDTD and implicit FDTD algorithms are introduced, and the numerical dispersion characteristics and stability conditions of the algorithm are analyzed. Secondly, the convolution perfectly matched layer (Convolutional Perfectly Matched Layer,CPML) and the methods of introducing different excitation sources are introduced. Finally, the classical thin wire model in FDTD is introduced. (2) the classical thin wire algorithm in FDTD is extended to Leapfrog ADI-FDTD, which is suitable for simulating monopole thin wire antenna on large ship platform. Based on the VonNeumann method and a large number of numerical experiments, the unconditional stability of the algorithm is semi-analytically proved. The algorithm is applied to the simulation of electromagnetic compatibility problems on large ship platforms, including the calculation of near-field coupling effects (S parameters) between antennas and the far-field radiation pattern of antennas. The voltage induced by external plane waves and the distribution of current density on the surface of the ship's platform are obtained. (3) A dual-frequency double-circularly polarized eccentric annular microstrip antenna is designed, and the working mechanism of the antenna is deeply investigated. The effect of different structure parameters on antenna performance is also studied. An equivalent circuit of lumped elements is proposed to understand the working mechanism of antenna. A set of empirical formulas and design instructions are given to simplify the design process. Finally, the antenna is made and measured, and the results are in good agreement with the simulation.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TN822
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本文編號(hào)：2373188