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Title: | 微型化壓電超晶格HF天線 Piezoelectric Superlattice Polariton-based Miniaturized HF Antennas |
Authors: | Chin-Hsiang Lu 呂晉祥 |
Advisor: | 劉建豪(Chien-Hao Liu) |
Keyword: | 高頻天線的微型化,壓電超晶格,共振模態,週期極化鈮酸鋰,鋯鈦酸鉛,阻抗匹配, miniaturization of HF band antennas,piezoelectric superlattices,resonant mode shape,periodically polarized lithium niobate,PZT,impedance matching, |
Publication Year : | 2019 |
Degree: | 碩士 |
Abstract: | 現今的HF(high frequency)天線一般廣泛運用在軍事或航空等長距離傳輸,因為在空氣中,天線的低頻傳輸損耗較小,但是較長的共振波長也造成高頻天線的外型尺寸過大,這會造成一些使用上的不便。因此HF天線的微型化一直是研究的重點,本研究提出利用極子波於壓電超晶格材料傳遞達成天線的微型化。
由於在壓電超晶格內,電磁波與機械波會互相耦合並且產生極子共同在材料內傳遞。在無因次化頻率Ω = 1的位置,極子的特性會近似於機械波的特性,也就是聲子,我們將壓電超晶格天線的共振頻率命名為Ω_b,也就是Ω = 1,並且透過之後的輻射量測實驗來找出壓電超晶格天線的輻射頻率Ω_r。所以我們要找出此壓電超晶格的共振模態,藉由模擬軟體的幫助,我們可以找到壓電超晶格的共振頻率,以及在此頻率下所產生的表面電荷分布,這有幫助於我們設計之後的量測夾具。在此研究中,因為頻率變低,減少過多的週期數會影響壓電超晶格極子天線的效能,因此我們提出另一種形式的壓電超晶格,材料分別為週期極化鈮酸鋰與鋯鈦酸鉛。 在完成兩種壓電超晶格天線的模擬與製作後,我們會設計適合的量測夾具,方便我們之後的測量。我們會先測量壓電超晶格天線的反射係數,來確認它無因次化共振頻率的位置,在藉由輻射量測已確認輻射頻率的位置。為了增加壓電超晶格天的輻射效率,我們使用變壓器來做阻抗匹配,使其更接近饋入阻抗並增加饋入效能。 The HF band antennas have been widely used in civil and military communications recently. The lower resonant frequency of HF band antennas can reduce the energy loss during the transmission. Because of the long resonant wavelength, the size of the HF band antennas is gigantic. For the more convenient applications, the miniaturization of HF band antennas is becoming important. Thus, we want to reduce the size of HF band antennas by the piezoelectric superlattices. In this study, we use the characteristics that the electromagnetic and acoustic wave will couple in piezoelectric superlattices. The coupling phenomenon produces the polaritons. At the normalized frequency Ω = 1, the polaritons act like the acoustic wave. Then, we need to find the resonant mode shape of piezoelectric superlattices. With the simulation, we know the resonant frequency and the surface charge produced by the piezoelectric superlattices. We will discuss two types of acoustic wave in piezoelectric superlattices, which are periodically polarized lithium niobate (PPLN) and lead zirconate titanate (PZT) antenna. After fabricating the two piezoelectric superlattice antennas (PSAs), we measure the S-parameters of them to ensure the normalized frequency Ω_b, and then conduct the radiation experiments for the radiation frequency Ω_r. In order to enhance the radiation efficiency of PSAs, we use the transformers to do the impedance matching. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/21664 |
DOI: | 10.6342/NTU201901019 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 機械工程學系 |
Files in This Item:
File | Size | Format | |
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ntu-108-1.pdf Restricted Access | 14.39 MB | Adobe PDF |
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