螺旋滤波器设计

1、螺旋滤波器 主要特点 1.)频率范围：几十MHz到到大约2GHz； 2.)带宽：0.5%-超过50%; 3.)低损耗，相比同频率范围的LC分立元件滤波器具有低损耗的特点(螺旋谐振腔无载Q值能达到1000)； 4.)宽带宽，相对一同频率范围的SAW、Crystal滤波器能实现更宽的带宽；5.）小尺寸，相比于同频率范围的同轴腔滤波器尺寸小很多，例如，一个54MHz的谐振(Q=550)，同轴腔为4.5英尺0.7英寸，而螺旋滤波器为2英寸1.5英寸；6.）加工容易，适合大批量生产。 应用领域1.)卫星通信(1) (下图为2个螺旋滤波器，能很好达到选择性和群时延要求)(1).Reference：High

2、 Performance Helical Resonator FiltersBy Ming Yu and Van Dokas Microwave Conference, 2004. 34th European Publication Date: 13 Oct. 2004Volume: 2, On page(s): 989- 992 ISBN: 1-58053-992-0 图. 2. 7-1 螺旋滤波器图. 1. 8-2-2 螺旋滤波器2.)应用于双工器(1)、多工器、倍频器、变频器、放大器、振荡器(2)等电路单元。(1).Reference: R. Levy and K. Andersen “

3、An optimal low loss HF diplexer using helical resonators”, Microwave Symposium Digest, 1992., IEEE MTT-SInternational, 1-5 June 1992, Pages:1187 - 1190 vol.3(2).Reference: Everard, J.K.A.; Cheng, K.K.M.; Dallas, P.A.; “High-Q helical resonator for oscillators and filters in mobile communications sys

4、tems”, Electronics Letters ,Volume: 25 , Issue: 24 , 23 Nov. 1989 Pages:1648 1650图. 3. 一个典型的螺旋滤波器产品不同结构的螺旋滤波器1. 双模螺旋滤波器(1)(1).Reference:Kwok, R.S.; Fiedziuszko, S.J.; “Dual-mode helical resonators”, Microwave Theory and Techniques,IEEE Transactions on , Volume: 48 , Issue: 3 , March 2000 Pages:474 -

5、 477图. 4. 双模螺旋滤波器(helix: copper;core: Teflon ;Cavity:aluminum).图. 5. 处理响应曲线(IR: 1.8dB;BW: 10MHz ;Qu:1400). 螺旋滤波器主要部件：螺旋谐振腔(见下图)d = Mean helix diameter (cm)C = Inside diameter of circular shield (cm)S = Length of square shield side (cm)H = Height of shield (cm)f = Resonant frequency (MHz)Q = Unloaded

6、 Q of an air-filled resonatorQd = Unloaded Q of a dielectric-filled resonatorN = Number of turns on helixp = Helix pitch (turns/cm)Z0 = Characteristic impedance of air-filled helical transmission line ()Zd = Characteristic impedance of dielectric-filled helical transmission line ()g = Wire diameter

7、and also space between turns (cm)tan(d) = Loss tangent of dielectric material 螺旋谐振腔设计：1.)空气填充2.)介质填充设计曲线螺旋谐振腔谐振频率精确计算(1)图.10.螺旋腔体结构1.)基模频率f1：2.)二次模频率f2：3.)三次模频率f3：(1).Reference: Resonant frequencies of helical resonators by Antoniuk, J.; Zukocinski, M.; Abramowicz, A.; Gvvarek, W.; 不同的螺旋线圈形式(1)(1).R

8、eference: US Pat.NO 3936776 “Interspersed double winding helical resonator with connections to cavity” by John Robert Sundquist Feb 3, 1976优点：抑制奇次谐波，提供更好的腔体间的 耦合特性图.11.Helical绕线形式图.12.提高了奇次谐波的抑制扩展螺旋滤波器带宽的途径(1).Reference: US Pat.No. 4284966 Wide bandwidth helical resonator filterBy Wanat; Ronald J. (

9、Elgin, IL) August 18, 1981 图.13.具体的腔体结构1.)缩短腔体距离(1)2.) 在耦合窗加介质(1)，如：alumina、polypropylene、 teflon等；图.14.加介质后的螺旋滤波器图.15.对应响应(1).Reference: US Pat.NO. 4365221 Helical resonator filter with dielectric apertures By Vizmuller; Peter (Thornhill, CA) December 21, 1982 3.)将螺旋线圈的开路端增大；4.)在耦合窗加U型耦合圈。参考文献参考文献1 Peter Vizmuller, “Filters with Helical and Folded Helical Res