有鑑於傳統的帶拒濾波器(Notch Filter)不易積體化且功率消耗大，所以本論文之目的，則是以表面聲波為基礎來製作一表面聲波帶拒濾波器(Surface Acoustic Wave Notch Filter)。雖然過去已有些研究討論，但在其結構上往往需外加集總元件電阻R、電容C、電感L，而使元件結構呈現複雜化及不易於積體化。所以我們提出了一種簡單平面型的結構來實現表面聲波帶拒濾波器，使其具有較小尺寸和較輕重量的特性且易於積體化。吾人利用表面聲波的原理，設計交叉指狀電極轉換（Interdigital Transducer，IDT）與傳輸延遲線（Delay Line）耦合的電路結構，使其達成帶拒濾波器之特性。
以本文為例，則是以此結構採取指叉電極寬度為8μm，以半導體中的微影、曝光及蒸著(Evaporation)的製程技術，製作於128˚ rotated YX-cut Lithium Niobate（鈮酸鋰，LiNbO3）壓電材料基板上，其所呈現的中心頻率為 113.4 MHz 且3dB頻寬約為400 KHz（BW=0.36%）、插入損失（S21）約為 -10.583 dB 的帶拒濾波效果。
經由軟體Microwave Office模擬與製程結果比較發現，隨著IDTs之重疊長度、對數及傳輸延遲的改變，可調變濾波器之插入損失及頻寬，可應用於阻絕其它訊號的干擾。除此之外，更解決了傳統RLC濾波器之不易積體化、消耗功率等問題；且符合通訊元件低成本、製作容易、體積小的需求。

Although Surface Acoustic Wave Notch Filter was investigated in the past, the structures of these devices often needed the extra lumped-element : resistance R、capacitance C and inductance L so that the devices are complex and integrated hardly. From this, we offer a simple planar structure of the SAW notch filters that have smaller size and can be fabricated easily. It has several advantages such as easy-integrated; smaller size and no power dissipation. We adopt the interdigital transducers and delay line to fabricate the SAW notch filter. In this paper, we use an interdigital transducer finger width 8 mm with conventional photolithography process; lift-off technique; piezoelectric materials to fabricate on the 128° rotated YX-cut Lithium Niobate (LiNbO3). Finally, we get the frequency responses of the SAW notch filter: the center frequency 113.4 MHz; the 3dB bandwidth 0.36 %; the insertion loss S21= –10.583 dB.

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