【正文】 內(nèi)容包括生成版圖中包含原理圖中有效的原件數(shù)目等信息， 如圖 ， 確認(rèn)其內(nèi)容與原理圖相同后單擊 [OK]， 完成版圖的生成。由濾波器原理圖生成的版圖如圖所示。 圖 版圖生成圖 仿真 （ 1） 為了進(jìn)行 S參數(shù)仿真，需要在濾波器輸入輸出端添加兩個(gè)端口。 陜西理工學(xué)院畢業(yè)論文 第 22 頁 共 43 頁 圖 在版圖中添加兩個(gè)端口 （ 2） 在版圖設(shè)計(jì)窗口中 單擊工具欄中的 圖標(biāo) ，打開仿真設(shè)置對(duì)話框， 單擊左側(cè)欄中的[Frequency plan]如圖 。 1. Sweep Type=Linear，表示掃描類型為線性的 2. Sart=，表示頻率掃描的起始頻率為 ； 3. Stop=，表示頻率掃描的終止頻率為 。 （ 4） 單擊【 Simulate】按鈕開始進(jìn)行仿真。等待數(shù)分鐘后仿真結(jié)束，仿真結(jié)果將出現(xiàn)在數(shù)據(jù)顯示窗口中。 圖 (a) 11S 參數(shù) 圖 (a) 21S 參數(shù) 由 圖 可以看出： ? 中心頻率為 ，滿足技術(shù)指標(biāo)。 陜西理工學(xué)院畢業(yè)論文 第 24 頁 共 43 頁 ? m3在 GHz衰減為 20dB； m4在 20dB滿足技術(shù)指標(biāo)。 3D 圖 生成版圖的 3D圖 步驟： 選擇菜單中的 [EM]—— [3D EM Preview]或點(diǎn)擊圖標(biāo) 運(yùn)行，即生成版圖 3D 圖。 圖 版圖 3D 圖（ a） 圖 版圖 3D 圖（ b） 陜西理工學(xué)院畢業(yè)論文 第 25 頁 共 43 頁 由原理圖產(chǎn)生的仿真曲線初始不能滿足指標(biāo)要求，利用 ADS 進(jìn)行多次全局優(yōu)化后，得到的仿真曲線如圖 。本文介紹了基于 ADS設(shè)計(jì)耦合微帶線帶通濾波器的方 法，傳統(tǒng)設(shè)計(jì)方法因?yàn)樾枰楸砑扒€擬合來完成，工作量大，而且設(shè)計(jì)精度不高。簡化了設(shè)計(jì)，提高精度，降低成本。 4 總結(jié)與展望 伴隨著微波通信領(lǐng)域技術(shù)的飛速發(fā)展，未來的濾波器需要從現(xiàn)在通信系統(tǒng)的工作頻率向更短波長，主要是毫米波段轉(zhuǎn)變，以避免在低頻段的擁擠的問題 , 微帶線濾波器因其體積小，結(jié)構(gòu)簡單，加工方便，成本低等優(yōu)點(diǎn) 。 本篇論文以研究濾波器為基礎(chǔ)，深入展開微帶線帶通濾波器的結(jié)構(gòu)，從而較深層次地分析微帶線系列濾波器的設(shè)計(jì)、軟件優(yōu)化等方面的內(nèi)容。同時(shí)給出了設(shè)計(jì)濾波器的設(shè)計(jì)實(shí)例以及對(duì)一些公式作了推導(dǎo)工作。材料特性、工藝參數(shù)、微帶濾波器的封裝腔體等方面的偏差，都對(duì)濾波器的參數(shù)性能有很大的影響?；牧系慕殡姵?shù)、厚度以及介質(zhì)損耗角等參數(shù)稍有變化，就會(huì)影響濾波器的整體性能指標(biāo)，因此在設(shè)計(jì)時(shí)應(yīng)充分地把材料的這些影響因素考慮進(jìn)去，使濾波器的設(shè)計(jì)更趨合理 ]23[ ?；厥姿哪甑膶W(xué)習(xí)成長經(jīng)歷，充滿了老師和朋友同學(xué)的關(guān)心與愛護(hù)，在這個(gè)終于順利撰寫完成我的畢業(yè)論文的時(shí)候，對(duì)曾經(jīng)給予我?guī)椭凸膭?lì)的父母、師長、同學(xué)、朋友致以衷心的感謝。本篇論文是在賈老師的悉心指導(dǎo)下完成的。你們不僅在學(xué)習(xí)上給予了我無私的幫助，在生活上也給我留下了美好的回憶。最后我特別要將誠摯的謝意獻(xiàn)給我的家人，感謝他們多年來對(duì)我的關(guān)心、照顧、理解和支持。 陜西理工學(xué)院畢業(yè)論文 第 28 頁 共 43 頁 附錄 A 外文文獻(xiàn) COUPLED LINE FILTERS The parallel coupled transmission lines discussed in Section (for directional couplers) can be used to construct many types of filters. Fabrication of multisection bandpass or bandstop coupled line filters is particularly easy in microstrip or stripline form for band widths less than about 20%. Wider bandwidth filters generally require very tightly coupled lines, which are difficult to fabricate. We will first study the filter characteristics of a single quarterwave coupled line section, and then show how these sections can be used to design a bandpass filter [7]. Other filter designs using coupled lines can be found in reference [1]. Filter Properties of a Coupled Line Section A parallel coupled line section is shown in Figure , with port voltage and current definitions. We will derive the opencircuit impedance matrix for this fourport work by considering the superposition of even and oddmode excitations [8], which are shown in Figure . Thus, the current sources 1i and 3i drive the line in the even mode, while 2i and 4i drive the line in the odd mode. By superposition, we see that the total port currents, iI , can be expressed in terms of the even and oddmode currents as 1I = 1i + 2i , () 2I = 1i 2i , () 3I = 3i 4i , () 4I = 3i + 4i . () First consider the line as being driven in the even mode by the 1i current sources. If the other ports are opencircuited, the impedance seen at port 1 or 2 is lβjZZ eein co t 0= () The voltage on either conductor can be expressed as )(c os2=+[=)(=)(_+)()(+11 ___zlβVeeVzvzvelzβjlzβjeba () so the voltage at port 1 or 2 is eineba ZilβVvv 1+11 =c o s2=)0(=)0( This result and () can be used to rewrite () in terms of i1 as 1_0_11 s in )(c os)()( ilβ zlβjZzvzv eba == () 陜西理工學(xué)院畢業(yè)論文 第 29 頁 共 43 頁 （ a） (b) (c) FIGURE Definitions pertaining to a coupled line filter section. (a) A parallel coupled line section with port voltage and current definitions. (b) A parallel coupled line section with even and oddmode current sources. (c) A twoport coupled line section having a bandpass response. Similarly, the voltages due to current sources 3i driving the line in the even mode are 30_33 s inc os=)(=)( ilβ zβjZzvzv eba () Now consider the line as being driven in the odd mode by current 2i . If the other ports are opencircuited, the impedance seen at port 1 or 2 is lβjZZ oin cot= 0_0 () The voltage on either conductor can be expressed as )(c os2=+[=)(=)( _+0)()(+02_2 ___ zlβVeeVzvzv lzβjlzβjba () Then the voltage at port 1 or port 2 is 02+02_2 =c o s2=)0(=)0( inba ZilβVvv This result and () can be used to rewrite () in terms of 2i as 2_0_2_2 s in )(c os=)(=)( ilβ zlβjZzvzv oba () Similarly, the voltages due to current 4i driving the line in the odd mode are 陜西理工學(xué)院畢業(yè)論文 第 30 頁 共 43 頁 40_4_4 s inc os=)(=)( ilβ zβjZzvzv oba () The total voltage at port 1 is θiZiZjθiZiZj vvvvV eeee aaaa c s c)+(c ot)+(= )0(+)0(+)0(+)0(= 4030_2020_43211 () where the results of (), (), (), and () were used, and θ = β .Next, we solve () for the i j in terms of the I s: 1i =21 ( 1I ＋ 2I ), () 2i =21 ( 1I － 2I ), () 3i =21 ( 3I ＋ 4I ), () 4i =21 ( 4I － 3I ), () and use these results in (): θIZIZIZIZjθIZIZIZIZjVooeeooeec s c)++(2=c o t)++(2=30_404030_20_102020_1 () This result yields the top row of the opencircuit impedance matrix [Z ] that describes the coupled line section. From symmetry, all other matrix elements can be found once the rst row is known. The matrix elements are then θZZjZZZZ oe c ot)+(2==== 00_44332211 () θZZjZZZZ oe c ot)(2==== 0__0_43342112 () θZZjZZZZ oe c s c)(2==== 0__0_42243113 () θZZjZZZZ oe c s c)+(2==== 00_32234114 () A twoport work can be formed from a coupled line section by terminating two of the four ports with either open or short circuits, or by connecting two end