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Title: | 極寬頻可調拉伸式頻率選擇表面之大面積應用 Ultra-wide Band Tuning Stretchable Frequency Selective Surface for Large-scale Application |
Authors: | Po-Wen Lin 林柏文 |
Advisor: | 劉建豪(Chien-Hao Liu) |
Keyword: | 可調頻率選擇表面,軟性材料,液態金屬嵌入,超寬頻可調, Frequency Selective Surface (FSS),embedded Liquid metal,stretchable silicon,ultra-wideband tuning,band-stop Filter (BSF), |
Publication Year : | 2020 |
Degree: | 碩士 |
Abstract: | 在這項研究中,我們提出了一種可拉伸式頻率選擇表面,由液態金屬組成,並嵌入的高度可拉伸的聚合物Ecoflex中。 Ecoflex是一種有機矽基聚合物,具有高達900%的拉伸範圍。為了實現寬頻調變,每個單元結構都設計成沙漏形狀的迴圈,並在內嵌入金屬液體。通過施加外部應力,由於泊松比的影響,可拉伸式頻率選擇表面伸長並且身長比從正方形變為矩形。在拉伸時,金屬液體保留在矽膠基板的孔洞內並根據孔道的變形而變形成符合孔道的尺寸。根據等效電路模型,單元結構變形將導致單元結構等效之電容及電感值造成共振頻率偏離。
本研究設計,製造和測試了尺寸為16乘16單元結構的原型。使用網絡分析儀(VNA)在微波暗室中測量頻率選擇表面的頻率響應。結果顯示,當測量頻率選擇表面受到水平拉伸時,帶阻移動到較低頻率。同樣的,當測量頻率選擇表面受到垂直拉伸時,帶阻移動到較高頻率。帶阻的可調值為7 GHz(以可調比例表示為69.31%)。可調頻率的移動範圍完全覆蓋X波段和C波段和Ku波段的一部分。由於本篇研究提出的頻率選擇表面不需要任何電子元件或移動物件,因此具有在惡劣環境下操作的能力。與常用的可調頻率選擇表面相比,所提出的的頻率選擇表面具有緊湊的尺寸,易於驅動的特性以及超寬的頻率可調範圍。 In this research, we proposed a stretchable FSS composed of liquid metal embedded within a commercial-available highly stretchable polymer, Ecoflex. Ecoflex is a silicone-based polymer with a large strain of up to 900%. In order to achieve wide-band tuning, each unit cell was designed to have a sandglass-like shape and embedded with metallic liquids. By applying external stress, the FSS elongated and the aspect ratio of the FSS change from square to rectangle due to Poisson's ratio. While stretching, the metallic liquid retained within the substrate and flew according to the deformed channels, and the resonance frequency deviated as the FSS being deformed. A prototype with a dimension of 16 by 16 unit cells was designed, fabricated, and tested. The frequency response of the FSS is measured in the microwave chamber by using the vector network analyzer (VNA). It was demonstrated that the stop-band shifted to the lower frequency while the FSS was stretched horizontally. Likewise, the stop-band shifted to the higher frequency while the FSS was stretched vertically. The total deviation of the stop-band is 7 GHz (69.31% in terms of fractional bandwidth). The shifting range of the frequency completely covers the X-band and a portion of the C-band and the Ku-band. And an experiment was conducted to test the ability to suppress the scattering from different directions. Since the proposed FSS does not require any electronic components or moving parts, it has a much higher possibility to survive in a harsh environment. Compared to the commonly-used electronic tunable FSSs the proposed FSS has a compact size, easy actuation method and ultra-wide tuning range. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/74708 |
DOI: | 10.6342/NTU202000016 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 機械工程學系 |
Files in This Item:
File | Size | Format | |
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ntu-109-1.pdf Restricted Access | 6.66 MB | Adobe PDF |
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