Synthesized Crystal Structure and Microwave Characteristics in Bandpass Filter of Dielectric Resonator Ba2 Ti9 O20 Ceramics

Abstract

本研究已成功設計出一種消散型帶通濾波器，其共振頻率f��=5.10 GHz及帶寬 △f=0.0345GHz，可用來測試Ba�� Ti�板�洹鰹ぜ野峎陘飪q共振器的可行性。長方形共振腔的寬度影響元件之微波截止頻率甚為顯著，然而共振腔長度對元件的影響則較不明顯。另一方面，在共振腔中插入介電物質會降低截止頻率。所通過微波頻帶的中心頻率與介電共振器的共振頻率相同。至於合成Ba�� Ti�板�洶飪q共振器材料的方法，以有機金屬物噴霧熱解法較優於共沉法。利用噴霧熱解法可以完全消除BaTi�淋�炊咷aTi�Μ�V中間相的形成。

An evanescent bandpass filter with resonance frequency f�� =5.10 GHz and band width △f=0.00345 GHz has been designed for testing the feasibility of using Ba�� Ti�� O�� materials as dielectric resonators. The width of the rectangular cavity was found to affect the cutoff frequency of the device most significantly, while the length of the cavity has least influence. The insertion of the dielectrics, on the other hand, lowers the cutoff frequency. The center frequency of the passing band is the same as the resonance frequency of the dielectric resonators. As to the synthesis of the materials for dielectric resonators, i.e., Ba�� Ti�� O��, the sprayed pyrolysis of metallo-organic precursors was found superior to coprecipitation process. The formation of intermediate phases, i.e. BaTi�� O�� ,BaTi�� O�V , found in coprecipitation process can be completely eliminated by sprayed pyrolysis technique.