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    Title: 直交表於UWB天線設計上的應用
    Other Titles: Application of orthogonal array to the design of UWB antennas
    Authors: 楊尚嶧;Yang, Shang-Yi
    Contributors: 淡江大學電機工程學系碩士班
    李慶烈;Li, Ching-Lieh
    Keywords: 平面單極天線;超寬頻天線;田口法;Planar;monopole antenna;Ultra wide band;Taguchi method
    Date: 2011
    Issue Date: 2011-12-28 19:21:40 (UTC+8)
    Abstract: 本篇論文探討以直交表(Orthogonal Array,OA)進行迭代設計,目標在設計一符合FCC規格頻段要求(3.1GHz~10.6GHz)的超寬頻(UWB)單極小天線之設計,期待能在有限且少量的迭代次數內,使天線特性達到UWB頻段的要求。本研究採用平面式的結構,針對厚0.8mm的FR4基板(相對介電係數為4.4、Dielectric Loss Tangent為0.02)的環境來進行設計、模擬,並和實作結果相驗證,以快速研製一體積小、重量輕、低成本、容易製作的超寬頻帶(UWB)單極小天線。
    首先依據UWB單極天線的結構,選定待設計/調控之結構參數以及每一參數之位準(level)個數,據此建立一適當的直交表。再以電磁模擬軟體進行直交表所列的部份因子實驗及少量而有限次數的迭代,針對模擬結果計算不同實驗之適應值,以進行天線參數最佳化,並規劃在少量而有限的迭代次數後,判斷是否已達到UWB頻段規格要求的目標。
    與其它參數設計法則相較,直交表最大的特色在於每個參數因子的位準出現的次數均等,當以此特性來取代全因子實驗,此方法可達到降低搜尋次數、加快參數設計流程,又可維持對問題解空間的進行全域搜尋。為此,一般皆藉由直交表均勻搜尋的概念,再結合逐步縮減搜尋範圍(Range Reduction)的技巧,以落實最佳化搜尋。
    本論文除了根據待定參數因子在某些選定頻率點的回應表進行最佳化的迭代搜尋,並引進隨機亂數(高斯分佈)以修正參數因子的位準(level)值,藉由此一在直交表結合引入亂數的作法,以及多段式的範圍縮減技巧等,目的在使其收斂過程更有效率及/或收斂結果更接近全域之最佳解。
    This thesis investigates a new antenna design method by utilizing the orthogonal array (OA) for a small ultra-wideband (UWB) monopole antenna that meets the frequency band (3.1GHz~10.6GHz) of FCC requirements. By application of the OA in the design course of iterative procedure, it is found that the antenna characteristics can meet the requirements of UWB band within limited and relatively few iterations. In this study, a planar structure is tested under the enviroment of FR4 substrate with thickness of 0.8mm and relative dielectric coefficient 4.4, dielectric loss tangent 0.02. An UWB antenna is designed, simulated, and fabricated. The simulated results are verified by experimental ones. The goal is to examine a systematic approach to design an antenna structure by avoiding blind try-and -error. In this case, the objective is to quickly develop a small , light weight, low cost UWB monopole small antenna.
    At first, based on the structure of the UWB monopole antenna to be examined, we can select suitable design/control parameters, and reasonable number of level for each parameter, thus an appropriate orthogonal array is established. Then through electromagnetic simulation software we can conduct the fractional factorial “experiments“ listed in the orthogonal array such that the fore-mentioned limited and relatively few number of iterations can be performed. The simulation results can then be used to calculate the fitness value of each experiment for sucessive optimization of the antenna parameters. At the end of each iteration/generation, the best canditate is updated and checked to see whether it has reached the design goal – to meet the requirements of UWB frequency band.
    As compared to other methods of parameter design, the distinguished characteristic of utilizing orthogonal array for parameter design is that the number of occurrences of each parameter level is the same and/or equally-balanced for every parameter. When this method is employed to replace the full factorial experiment, it can reduce search times very effectively. In addtion to the speed up for the parameter design process, the method employed also maintain the global search for the solution space. To this end, the characteristic of uniform/balanced searching through the utilization of orthogonal array is combined with the technique of range reduction (gradual reduction of the search range iteratively) to implement the optimal search.
    This thesis not only carried out the iterative optimization search for the unknown design parameters according to the response table of the design parameters at several selected frequencies, but also proposed the introduction of the random numbers (Gaussian distribution) to modify the parameters levels. By the combination of random numbers with the orthogonal array, plus multi-stage technique of range reduction, the goal is aim to make the convergence process more efficient, within limited number of iterations, and/or the convergence result is closer to the optimal solution.
    Appears in Collections:[電機工程學系暨研究所] 學位論文

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