採用多級串接之週期性負載單元來增加順向耦合線耦合器之頻寬

本論文提出一個串接的架構來增加順向耦合線耦合器的頻寬。不同於多級反向或轉向耦合線耦合器需要奇數個耦合器並呈對稱型分佈來達到二輸出端埠間寬頻功率差及九十度相位差，本論文所提出的多級順向耦合線耦合器的串接設計則無此在耦合器數量上的限制，本論文將採用二級及三級串接的耦合線耦合器來應證所提出架構之實用性，並推導順向耦合線耦合器多級串接設計公式，每一級均給予適合的耦合量，以達到增加頻寬的目的。同時再以週期性結構來完成每一級順向耦合器的設計藉以縮小最終元件的尺寸。初步以ADS模擬傳輸線為基礎的模擬結果顯示，相較於單級且相同耦合量的耦合器本論文所提出的架構可提供較寬頻的輸出功率差，但由於採用微帶線為實際傳輸線的因素及週期性結構之集總元件的寄生參數的影響，必須藉由HFSS模擬軟體來修正其所導致的誤差。本論文將實作上述之二級、三級順向耦合線耦合器，來應證所提出的架構確實能增加順向耦合線耦合器的頻寬。

關鍵字

順向耦合線耦合器；頻寬；多級耦合器；週期性結構

並列摘要

This study presents a structure in series connection to enhance the bandwidth of codirectional coupled-line couplers. Unlike multisection contradirectional or transdirectional coupled-line couplers requiring odd number of sections in a symmetrical form to achieve the goal of broadband power difference as well as phase difference of 90o between two output ports, the proposed design featuring multisection codirectional coupled-line couplers has no restriction on the number of the couplers for that performance. Practical examples with two and three coupled-line couplers in tandem are presented for the proposed structures with appropriate coupling coefficients assigned to each coupler. Periodic structures are used to implement each coupled-line couplers for the purpose of size reduction. The initial simulation results based on ideal transmission lines indicate, compared to a single transdirectional coupled-line coupler of the same coupling coefficient, the two-section transdirectional coupled-line couplers offer the desired wider bandwidths. Additional modifications to the values of the periodic elements must be made to account for the parasitic effects and the fact that microstrip lines are used instead. The final designs will be implemented and measured to verify the potential of the proposed structures to enhance the bandwidths of codirectional coupled-line couplers.

並列關鍵字

Bandwidth ； codirectional coupled-line couplers ； multisection coupler ； periodical structures

參考文獻

[14]康誠哲，週期性負載轉向耦合器頻寬之改善，碩士論文，國立台北科技大學，台北，2013。

[3]C. I. Shie, J. C. Cheng, S. C. Chou, and Y. C. Chiang,“Transdirectional coupled-line couplers implemented by periodical shunt capacitors,” IEEE Trans.Microw. Theory Tech., vol. 57, no. 12, pp. 2981-2988, Dec. 2009.

[5]S. K. Hsu, J. C. Yen, and T. L. Wu, “A novel compact forward-wave directional coupler design using periodical patterned ground structure,” IEEE Trans. Microw. Theory Techn., vol. 59, no. 5, pp. 1249–1257, May 2011.

[6]S. K. Hsu, C. H. Tsai, and T. L. Wu,“A Novel Miniaturized Forward Wave Directional Coupler With Periodical Mushroom Shaped Ground Plane,”IEEE Trans. Microw. Theory Techn., vol. 58, no. 8, pp. 2277-2283, Aug 2010.

[7]T. Fujii and I. Ohta, “Size reduction of coupled microstrip 3 dB forward couplers by loading with periodic shunt capacitive stubs,”IEEE MTT-S INT. Microw. Symp. Dig., pp. 1235-1238, Jun. 2005.

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採用多級串接之週期性負載單元來增加順向耦合線耦合器之頻寬

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