【摘要】：為了滿足通信、雷達和導航應用的需求,現代大型艦船平臺上通常安裝著各種電子系統。這些電子系統的近場互耦會導致復雜的電磁環(huán)境效應,使得系統整體性能變差。另外,這些電子系統和艦船平臺對外來電磁干擾(Electromagnetic Interference,EMI)非常敏感,嚴重時會導致系統失效。解決這些電大尺寸、多尺度的平臺級電磁兼容(Electromagnetic Compatibility,EMC)問題需要高效、精確的數值計算方法。時域有限差分算法(Finite-Difference Time-Domain,FDTD)已經被大量應用于解決這些問題,然而由于FDTD的時間步長受限于空間網格大小,傳統的FDTD方法在求解這類問題時計算效率受到嚴重限制。本文針對大型艦船平臺上的電磁兼容問題,拓展了單步無條件穩(wěn)定時域有限差分算法(Leapfrog Alternately-Direction-Implicit FDTD,ADI-FDTD),應用于艦船平臺上細線天線的精確仿真。本論文主要內容和創(chuàng)新點如下:(1)介紹了傳統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網格剖分,并分析了算法的數值色散特性和穩(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源的方法。最后介紹了 FDTD中經典的細導線模型。(2)將FDTD中經典的細導線算法拓展到Leapfrog ADI-FDTD中,適用于仿真大型艦船平臺上的單極子細線天線。基于VonNeumann方法和大量數值實驗,半解析地證明了該算法的無條件穩(wěn)定性。將該算法應用于仿真大型艦船平臺上的電磁兼容問題,包括計算天線之間近場耦合效應(S參數)和天線遠場輻射方向圖,以及有外來平面波輻照下天線端口感應的電壓和艦船平臺表面電流密度分布。(3)設計了一種雙頻雙圓極化偏心圓環(huán)微帶天線,對天線的工作機理進行了深入探究,并研究了不同結構參數對天線性能的影響。提出了一個集總元件等效電路以深入理解天線的工作機理,并給出一組經驗公式和設計指導以簡化設計流程。最后制作了天線實物并進行實驗測量,結果與仿真吻合較好。
[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.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN822
，

本文編號：2373188