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In-line mixed combline / TE01-mode dielectric resonator filter with wideband spurious suppression and cross coupling
|Authors: ||Chen, Hsueh-Han|
|Contributors: ||NTOU:Department of Electrical Engineering|
Mixed cavity (dielectric / coaxial combline);cross coupling;high order mode suppression;bandpass filter;waveguide evanescent mode
|Issue Date: ||2018-08-22T07:13:02Z
|Abstract: ||本論文結合了介質諧振器(Dielectric Resonator)與同軸梳型諧振器(Combline Resonator)，設計出中心頻率為6.35GHz、頻帶寬度為25MHz之混合腔帶通濾波器。介質諧振濾波器的優點為體積小、低損耗，但是有許多高階模態，而同軸梳型濾波器比介質諧振濾波器有較寬的無諧波帶寬，透過兩者的結合可以抑制介質諧振濾波器所產生的高階模態。 由於同軸梳型諧振器與介質諧振器之兩種模態電場方向不同，導致電磁能量無法直接傳遞。本論文利用不連續結構產生兩個互相垂直的波導管衰減模態，其中一個在相鄰兩共振腔內電場方向相同使電磁能量直接耦合，另一個則繼續通過鄰近的共振腔至下一個電場方向相同之共振腔，使交叉耦合產生。 因為擁有兩種模態傳遞，因此擁有雙模濾波器的特性，根據不連續結構位置的不同而使電場方向差180度，因此交叉耦合的正負也會有所不同，本論文透過模擬各種混合腔體組態以及不連續結構位置，分析此雙模濾波器之交叉耦合特性。|
In this thesis, a mixed resonator filter structure is proposed which consists of a combination of TE01 mode dielectric resonators (DR) and combline resonators for obtaining an improved spurious response performance. Based on the approach, a hybrid bandpass filter has been designed and implemented with the center frequency at 6.35 GHz and a bandwidth of 25 MHz. The DR filter has the advantages of small size and low insertion loss. However, its major drawback is the inferior spurious characteristics caused by the undesired modes in close proximity to the operating dominant mode. Combline resonator filter, by contrast, has much wider spurious-free stopbands as compared to conventional DR filter. Therefore, the mixed resonator filter configuration is suggested to suppress the spurious modes of the DR cavity and achieve high spurious performance. The E-field of the TEM mode resonating in the combline resonator is orthogonal with respect to the field of the TE01 mode in the DR loaded cavity. In order to establish a coupling between the combline and DR resonators, a proper waveguide discontinuity is introduced to generate an interaction between the orthogonal modes. In addition, a cross coupling can be generated between combline resonators since one of the orthogonal modes can by-pass the DR cavities. Due to the characteristic of dual modes transmission, we can design the filters with different cross couplings by changing the configuration of the mixed resonators. Besides, the field direction changes 180 degrees if the position of the discontinuous metal plates is changed to opposite wall. Therefore, the cross-coupling can be designed to be positive or negative value depending on the requirement. In this thesis, we also provide some simulation results for different configurations of the mixed resonators and the metal plates to explore the cross coupling characteristics.
|Appears in Collections:||[電機工程學系] 博碩士論文|
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