波导滤波器

电子科技大学贾宝富博士现代滤波器设计讲座（三）波导滤波器设计波导滤波器概述波导滤波器具有插入损耗低、功率容量大和容易批量生产的特点；波导滤波器的工作频率可以达到毫米波波段。主要用于卫星通讯、电子对抗和雷达系统。波导滤波器有以下几种类型：直接耦合波导滤波器；交叉耦合波导滤波器；带抑制谐振器的波导滤波器；使用非谐振结点的波导滤波器；使用过模谐振器的波导滤波器；凋落模波导滤波器；电子科技大学贾宝富博士现代滤波器设计讲座（三）腔体级联耦合波导滤波器对称膜片纵向条带方柱横向条带圆柱矩形波导滤波器常见类型波导滤波器设计举例设计参数：f0=15.35GHzBW=32MHzS11-20dBS21-40dB@f0±40MHz滤波器从14.9到15.35GHz连续可调BJ-140波导技术参数：a=15.8mm;b=7.9mm;工作频率范围：11.9~18GHz滤波器原型1a)Obtainlow-passprototypeparameters(gi)fromfilterspecifications(seee.g.Matthaei*)g0g1g3gn-1gn+1g2g4gnf0BWILRL*Matthaei,YoungandJones“Microwavefilters,impedance-matchingnetworks,andcouplingstructures”,ArtechHouse,Norwood,MA,1992K01K12K23Kn,n+1Z0AZ0BZ0Z0Z0Z0g/2g/2Example:f0=15.35GHzBW=32MHzS11-20dBS21-40dB@f0±40MHz6thorderChebychevfilterprototypeelementsg0=1.0000g1=0.8836g2=1.3966g3=1.7894g4=1.5528g5=1.6095g6=0.7667g7=1.1524带K变换器滤波器模型1b)CalculateK-inverters(band-passprototypeparameters)00201gicK01K12K23Kn,n+1Z0AZ0BZ0Z0Z0Z0g/2g/201010012AAKwKZgg,1,1012nnBnnBnnKwKZgg11,001,1,12iiiiiiiiiggwZZKK0200ffwgiiExample:K´01=0.0775K´12=0.0048K´23=0.0034K´34=0.003200cfK变换器的S参数在滤波器中心工作频率00jKAjK211222211221;121KSSKKSSjKK01K12K23Kn,n+1Z0AZ0BZ0Z0Z0Z0g/2g/22222221211;2111KKjKKSKKjKKK变换器计算模型利用对称面可以简化模型；计算K值；计算附加相移；21111212111111SKSSSK01K12K23Kn,n+1Z0AZ0BZ0Z0Z0Z0g/2g/22190argiS优化耦合系数Forallcouplings:OptimizecouplingtogivetherightK-invertervalueatthecenterfrequency11112212111111SKSKSSCouplingS21(dB)1-16.142-40.403-43.474-43.935-43.476-40.407-16.14diameteroffsetd1=2.50mmdo1=3.845mmd2=3.50mmdo2=3.135mmd3=3.50mmdo3=2.960mmd4=3.50mmdo4=2.972mmd5=3.50mmdo5=2.960mmd6=3.50mmdo6=3.135mmd7=2.50mmdo7=3.845mmK01K12K23Kn,n+1Z0AZ0BZ0Z0Z0Z0g/2g/2ddo优化谐振腔长度Forallresonators:calculateresonatorlength,finetuneuntilthestructureresonatesatthecenterfrequency2grl2121rlrK01K12K23Kn,n+1Z0AZ0BZ0Z0Z0Z0g/2g/2DennefigurenerIKKEforførsteresonatorr1215.3115.3215.3315.3415.3515.3615.3715.3815.3915.4-40-35-30-25-20-15-10frequency(GHz)S(dB)resonatorlengthl1=10.839mml2=11.346mml3=11.395mml4=11.395mml5=11.346mml6=10.839mm15.2415.2615.2815.315.3215.3415.3615.3815.415.42-90-80-70-60-50-40-30-20-10010frequency(GHz)S(dB)滤波器测试结果Designedat15.35GHzTunablefrom14.9to15.35GHzMeasuredat15.32GHz15.2915.315.3115.3215.3315.3415.35-6-5-4-3-2-10frequency(GHz)S21(dB)datacenteredonf0-40-30-20-100102030-60-50-40-30-20-100f-f0(MHz)S(dB)S11MeasuredS21MeasuredS11HFSSS21HFSSS11GoalS21Goal仿真与测试结果比较