臺灣博碩士論文加值系統

頻率選擇表面(FSS，Frequency Selective Surface)是由諧振單元沿一維或二維方向週期排列而成的無限大陣列，這種結構對不同頻率的電磁波有不同的反射或穿透能力，在航空和雷達領域具有廣泛應用，近年來己成為微波和天線學者們的一個主要研究方向。
本文在分析FSS 技術的特性，利用有限元素法結合三維電磁模擬軟體HFSS(High Frequency Structure Simulator)，做了以下研究工作:
為了研究FSS 傳輸性能的影響因素，選用了多種單元分別研究了多個因素對FSS 傳輸特性的影響。結果表明：增加單元尺寸及電磁波的入射角和介質層的加載使得共振頻率偏向低頻，介質層介電常數的影響要比介質層厚度的影響更大。
在模擬及實測上分析四種帶拒型頻率選擇表面的圖型，包含：環形貼片型、十字貼片型、矩形貼片型、耶路撒冷貼片型，基於這四種圖形，不同參數、不同基板的變化下，分析產生的特性及影響。在量測時因為發現常使用的玻璃纖維板(FR4)在高頻時的損耗較大，所以使用正切耗損失較低的Neltec板材做量測比較。所設計的四種不同型式的頻率選擇面的共振頻頻率為9.375GHz。
由結果可知在兩種板材的量測上皆有頻偏現象，但是使用Neltec板材下的共振頻率頻偏皆比FR4板材小且抑制性佳及頻寬較寬。環形FR4共振頻率偏移785 MHz，環形Neltec共振頻率偏移275 MHz，矩形 FR4共振頻率偏移670 MHz，矩形 Neltec共振頻率偏移435 MHz，十字型 FR4共振頻率偏移800 MHz，十字型Neltec共振頻率偏移385 MHz，耶路撒冷型 FR4共振頻率偏移1.04 GHz，耶路撒冷型Neltec共振頻率偏移575 MHz，在環形Neltec的共振頻率為9.6125 GHz，穿透值-56.31dB，頻寬為1.21 GHz，實驗結果可比較出環形貼片圖型是實作上較好的選擇，其實際的擇頻特性與效果上的影響是最小，不論共振頻率或頻寬都相當的穩定、且抑制性佳。在共振頻率、頻寬及抑制性的要求下，較容易達到規格要求。

Frequency selective surface (FSS) is an assembly of identical elements arranged in a one or two dimensional infinite array. This structure has different reflection or transmission capacity for the electromagnetic waves of different frequencies, it has many applications in aerospace and radar. Recently, FSS has become a major research focus of the microwave and antenna communities.
In this thesis, we analyze FSS technology character base on finite element method and High Frequency Structure Simulator (HFSS). We use various scenarios to study the factors in influencing the FSS transmission properties. The results showed that if we increase cell size, electromagnetic wave incident angle and dielectric layer thickness, the resonant frequency will drift to lower frequency. The factor of dielectric constant is more critical than the dielectric layer thickness in the FSS transmission issue.
We analyze band reject FSS simulation and measurement results for the following four structures: Ring patch, Cross patch, Rectangle patch and Jerusalem cross patch. Base on the shape types, we have analyzed the parameters and the dielectric layer for the four structures. Since FR4 has a high loss tangent, we have replaced with Neltec to improve the performance. A comparison between the two dielectrics will be made. The resonant frequency for the four structures is set at 9.375GHz. Four different FSS structures were subsequently fabricated and experimentations were carried out to study structures. In general, the measured results showed frequency up shift in comparing with the simulated results. However, structure based on Neltec showed better performance in term of transmission and a wider band width and a smaller frequency shift than that based on FR4. The frequency up shift for ring, cross, rectangle and Jerusalem cross on FR4/Neltec are measured to be 785 /275 MHz, 670/435 MHz, 800/385 MHz and 1.04 GHz/575 MHz, respectively. In this work, we show that ring patch on Neltec shows the best performance with resonant frequency at 9.6125 GHz, transmission coefficient of -56.31dB and a band width of 1.21 GHz.

摘要
Abstract
目次
圖目次
表目次
第一章 序論
1.1 研究動機與背景
1.2 內容提要
第二章 頻率選擇表面
2.1 頻率選擇表面簡介
2.1.1 以圖型結構分類
2.1.2 以傳輸特性分類
第三章 頻率選擇表面特性模擬分析
3.1 頻率選擇表面建立
3.1.1 HFSS模擬FSS的驗證
3.1.2 模型單元週期的選取
3.1.3 空氣場長度的界定
3.2 單元尺寸對FSS傳輸性能的影響
3.3 加載介質層對FSS共振頻率的影響
3.3.1 介質層厚度的影響
3.3.2 介質層介電常數的影響
3.3.3 介質層正切損耗的影響
3.4 入射角度對FSS的共振頻率的影響
3.5 不同週期陣列排列對FSS傳輸性能的影響
第四章 帶拒型FSS設計
4.1 不同樣式帶拒濾波FSS設計
4.2 FSS量測與模擬結果比對
4.2.1 量測方法
4.2.2 量測結果
第五章 結論
參考文獻

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