摘 要
近年來，移動(dòng)通信與個(gè)人通信業(yè)務(wù)進(jìn)入到了一個(gè)飛速發(fā)展的時(shí)期。高性能和小型化的微波電路是下一代無線通信系統(tǒng)的關(guān)鍵技術(shù)之一，電磁帶隙結(jié)構(gòu)(Electromagnetic Band Gap, EBG)的提出以及它在微波、毫米波領(lǐng)域的應(yīng)用，為系統(tǒng)的小型化和高可靠性提供了新的方法。本文的主要工作是根據(jù)EBG結(jié)構(gòu)的特點(diǎn)，分別討論了單層、雙層蝶形單元EBG結(jié)構(gòu)的頻率特性，并用粒子群優(yōu)化（Particle Swarm Optimization，PSO）算法對(duì)結(jié)構(gòu)進(jìn)行優(yōu)化設(shè)計(jì)。
本文主要工作如下：
1. 研究了一種蝶形單元的EBG結(jié)構(gòu)。通過微波雙端口網(wǎng)絡(luò)理論對(duì)EBG結(jié)構(gòu)進(jìn)行分析，得到它的頻率特性。由仿真計(jì)算結(jié)果可以看出，該EBG結(jié)構(gòu)的蝶形單元按照Hanning規(guī)律漸變時(shí)性能較好，此時(shí)－10dB帶寬為2.87GHz，相對(duì)帶寬為55%；而具有缺陷的EBG結(jié)構(gòu)在阻帶中形成一個(gè)具有一定帶寬的通帶，且通帶的頻率很容易調(diào)整。
2. 利用PSO算法對(duì)蝶形單元EBG結(jié)構(gòu)進(jìn)行優(yōu)化設(shè)計(jì)，使其頻率特性更好。在優(yōu)化過程中，為克服粒子群算法存在的早熟收斂和搜索精度低等問題，模擬生物克隆選擇中5%的B細(xì)胞自然消亡過程，在優(yōu)化算法進(jìn)化過程中基于混沌理論和變異原理設(shè)計(jì)了粒子更新算法，并按照模擬退火方法進(jìn)行更新后粒子的選擇。通過仿真計(jì)算可以看出，該電磁帶隙結(jié)構(gòu)具有良好的阻帶性能和相對(duì)帶寬，且優(yōu)化后通帶波紋明顯減小且基本對(duì)稱，頻率特性較好。
3. 研究了一種雙層EBG結(jié)構(gòu)，其上層為蝶形單元結(jié)構(gòu)，下層為接地板刻蝕圓孔結(jié)構(gòu)，通過仿真實(shí)驗(yàn)確定了圓的半徑及其與蝶形單元的相對(duì)位置。實(shí)驗(yàn)中為了減小通帶波紋，將圓的面積按照Chebyshev函數(shù)漸變，使得雙層EBG結(jié)構(gòu)具有較好的頻率特性。
4. 研究了一種雙層EBG結(jié)構(gòu)，其上層為蝶形單元結(jié)構(gòu)，下層為接地板刻蝕圓環(huán)結(jié)構(gòu)，利用PSO算法與HFSS軟件相結(jié)合對(duì)其進(jìn)行優(yōu)化設(shè)計(jì)，優(yōu)化后－10dB的相對(duì)帶寬和阻帶衰減值分別增加了22.69%和15.26%，通帶波紋減小了76.76%，優(yōu)化后結(jié)構(gòu)的頻率特性更好。

關(guān)鍵詞 電磁帶隙；蝶形單元；頻率特性；粒子群優(yōu)化












Abstract
The mobile communications and personal communications have been rapidly grown with wide applications in recent years. The microwave circuit with compact and high performance is one of the critical technologies in next generation wirelesse communication system. Electromagnetic bnad gap (EBG) and its applications in microwave and millimeter wave field present a new path for the communication system towards high compactness, performance and reliability. Based on the characteristics of EBG structure, the frequency chacteristics of single-layer and double-layer EBG structure with bow-tie units are discussed in this thesis respectively. And then particle swarm optimization (PSO) algorithm is used to optimize the structures.
The main research works are discussed as follows:
1. An EBG structure with bow-tie unit is researched in this thesis. Based on the theory of microwave 2-ports network, its frequency chacteristics is obtained. The simulaton results show that the performance of the EBG structure with bow-tie units is good when it tapers with hanning discipline. At this time, the bandwidth is about 2.87GHz at －10dB, and its relative bandwidth is 55%. The EBG structure with defect forms a passband with a certain bandwidth in the stopband, and the center frequency of passband may be adjusted easily.
2. The EBG structure with bow-tie units is optimized by using PSO algorithm. As we all know, the standard PSO has some shortcomings, such as premature convergence, searching precision lowness and so forth. In order to solve the problems, considering the simulation of natural death process of 5% B-cell in biology clone selection, this thesis proposes particles updating algorithm according to the theory of chaos and principle of mutation; and then selects the updated particles in terms of simulated annealing method. The simulation results show that the EBG structure with bow-tie units has a good stopband performance and large relative bandwidth. The passband ripples of the optimized EBG structure are very small and basically symmetrical. Frequency characteristic of the optimized EBG structure is very excellent.
3. A double-layer EBG structure is studied, including the bow-tie units etched on the upper layer and circles etched on the substrate. The radius of the circles and relative positions between circles and bow-tie cells are determined by simulation. For eliminating the passband ripples, the Chebyshev distribution is adopted to taper the area of the etched circles. This makes the frequency characteristics great.
4. A double-layer EBG structure is studied, including the bow-tie units etched on the upper layer and cirques etched on the substrate. PSO algorithm and the HFSS software are combined to optimize the sizes of the cirques. After optimizating, the relative bandwidth at －10dB and the attenuation of stopband are, respectively, increased 22.69% and 15.26%, and the passband ripples are reduced 76.76%. The frequency characteristics are very well after optimization.

Key Words Electromagnetic band gap; bow-tie unit; frequency characteristic; particle swarm optimization


目 錄
摘 要 I
ABSTRACT III
第1章 緒論 1
1.1 課題的研究背景和選題意義 1
1.2 課題的國內(nèi)外研究現(xiàn)狀 2
1.2.1 電磁帶隙結(jié)構(gòu)的研究現(xiàn)狀 2
1.2.2 粒子..