多層矩型波導帶通濾波器的研製

Design of Multilayer Rectangular Waveguide Band-pass Filters

沈澤旻(Tze-Min Shen)

指導教授 ： 吳瑞北

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.00349

摘要

本篇論文提出了數種多層矩形波導濾波器的架構，並實現在低溫共燒陶瓷的多層技術上。矩形波導共振腔的垂直金屬壁是以金屬連通柱列來等效。選擇末端開路的微帶線來激發開槽的共振腔，可免於使用貫孔的製程，簡化饋入電路，並且能避免直流的功率損耗。
首先設計的是具有柴比雪夫響應的濾波器，共振腔之間是藉由槽線來耦合，將槽線放在能大量切割表面電流的位置以達成較有效率的耦合。在多層結構中，適當的排列每一個共振腔的位置，可使得濾波器的面積縮小至僅為一個共振腔面積的大小。
另一種設計為準橢圓函數濾波器，要實現準橢圓函數的響應，一般是需要以電場耦合作為交錯耦合的路徑。因此在多層結構中，我們選擇在上下兩層共振腔的共有金屬層中央挖槽來實現電耦合。對於準橢圓函數濾波器，我們也提出以多層連通柱做為交錯耦合的新結構，並且能藉以縮小濾波器的面積至一個共振腔面積的大小。
我們將濾波器設計在ka頻段，比例頻寬約14%，並且實現在低溫共燒陶瓷的結構上。量測結果與模擬相當接近，濾波器的穿透損耗皆小於3dB，反射損耗也都優於11dB。

關鍵字

柴比雪夫 ； 準橢圓函數 ； 濾波器 ； 低溫共燒陶瓷 ； 矩形波導

並列摘要

This thesis proposes several type of vertically stacked waveguide filters in a multilayer low-temperature co-fired ceramic (LTCC) structure. The vertical metal walls of the waveguide resonators are realized by closely spaced metal filled vias. A λg/4 microstrip line open stub is used as the feeding structure. The microstrip lines are utilized to excite the resonator through coupling slot etched in the top metal layer of the cavity. The excitation using an open stub contributes to fabrication simplicity with no need to drill via-holes, and also avoids the DC power loss
First we design waveguide filters with Chebyshev response. Direct couples between adjacent cavities in different layers are achieved by narrow slots at the common wall. To efficiently couple two adjacent cavities, the narrow slot is placed near via wall of the cavity where it can largely interrupt surface current. Compared with planar waveguide filters, the circuit area of multilayered filters can be reduced to a single cavity size by an appropriate arrangement.
Another type of filter with quasi-elliptical function is designed on multilayer structures also. Conventionally, to realize quasi-elliptical response, electric fields coupling are needed for cross couple. This can be achieved by a square aperture at the center of the common wall between nonadjacent cavities in different layers. And it is not easy to achieve on planar circuits. Besides, a new cross couple structure composed of via holes is used for the other quasi-elliptical filter, and the circuit area can be reduced to a single cavity size also.
Filters are designed at Ka-band with fractional bandwidth about 14% and fabricated by LTCC technology. All the filters exhibit an insertion loss better than 3dB at the center frequency and a rejection larger than 11dB over the pass-band.

並列關鍵字

Chebyshev ； quasi elliptic ； filter ； LTCC ； rectangular waveguide

參考文獻

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