利用垂直線與分佈電容製作之寬頻化枝幹耦合器、以耦合量大小控制之雙頻枝幹耦合器、與基於左右手傳輸線之雙頻鼠競環折疊基板整合波導耦合器

Abstract

本論文演示了三種改進支幹耦合器或鼠競環耦合器的方法，其中，除了第一種寬頻化的改進只限定於支幹耦合器，因其餘兩種皆是用代換四分之波長傳輸線的方式，又兩種耦合器階是基於四分支波長傳輸線而組裝，因此，只要把設計的傳輸線代換到另一種元件，就能繼續使用該方法以改進。 前兩章就支幹耦合器與鼠競環耦合器的用途演進與基本原理介紹，第三章為一寬頻化支幹耦合器，利用額外分支與加入的平板電容，再透過數值解求出反射系數相較於頻率變化率最低的解，並將該結構實現於RO4003 20mil基板以驗證得到以反射系數定義的頻寬、輸出均衡的頻寬和輸出相位的頻寬分別增加11%、 3%與14%，驗證了這個設計的有效。 第四章為一基於耦合線之耦合強度之縮小化雙頻支幹耦合器，透過設計一色散的四分之一波長傳輸線，而該四分之一波長傳輸線傳播常數的曲線由一對耦合線所決定，就可做出雙頻的四分之一波長傳輸線，而這種傳輸線最大的優點是可以在有限的製程下把兩個頻段拉近，以本例來說，兩頻帶頻率比2時只需要耦合係數0.2的耦合線，再應用這個傳輸線組成支幹耦合器以實現支幹耦合器，最後再以Rogers Ro4003 60mil實現於0.9GHz與1.8GHz實作。 第五章則同樣為雙頻化設計，但應用於鼠競環耦合器，本章採用基於複合式左右手材料的折疊基板整合波導實現鼠競環，以用於高品質因數，高能量，高頻，低損耗又易於和印刷電路板製程整合的應用，本章以左右手傳輸線設計好鼠競環耦合器的一個四分支波長線段後，串接六個成環，並於Rogers 5880為基板，以Rogers Bonding Film3001壓合基板以實現折疊基板整合波導，經量測後，15dB反射，10度輸出相位差，0.5dB輸出大小平衡的兩個頻代頻寬幾乎都在3%與8%以上以驗証此結構的可行性。

In this thesis, three types of improvement on branch-line coupler or rat-race coupler are presented. Among these three types of improvement, one of them is suitable for branch-line coupler only. The other two are based on quarter-wavelength transmission line design, so these two are able to be applied on both branch-line coupler and rat-race coupler. The first two chapters introduce the applications, operation principle and theory of branch-line coupler and rat-race coupler. In the third chapter, Bandwidth-enhanced branch-line coupler using the center-loaded vertical line and distributed capacitors is presented. The branch-line coupler is realized through insertion of additional vertical branch as well as distributed capacitors patch on conventional branch-line coupler. Deriving all equations of this schematic, numerical method is applied to obtain optimized parameter. After fabricating this circuit on Rogers 4003 of 20mil, bandwidth of return loss, output balance and output phase are measuring 11%, 3% and 14% wider compared to conventional branch-line coupler. In the fourth chapter, we introduce artificial quarter wave transmission line and its application on branch-line coupler. The TL is dual-band operation based on a pair of couple-line. The higher the coupling coefficient, the closed these two band s are. By investigation of the relation between propagation constant and coupling coefficient, the coupling coefficient merely 0.2 is need to achieve band ratio 2 easy for fabrication. After that, this circuit is fabricated on Rogers Ro 4003 60mil. A CRLH-TL (Composite Right/Left Handed Transmission Line) dual-band rat-race coupler based on FSIW (Folded Substrate Integrated Waveguide) is presented in chapter 5. For purpose of high-Q, high-power, high frequency and low loss application, CRLH quarter-wave length transmission line based on FSIW is designed in this chapter. After that, we assemble six of this identical CRLH transmission line to build a rat-race ring and fabricating on Rogers 5880 bonded by Rogers Bond Film 3001. The measurement bandwidth of these two bands about 15dB return loss, 10 degree phase shift compared to central frequency and 0.5 dB output balance are above 3% and 8% respectively.