非对称宽边耦合CPW微波滤波器的散射参数设计

The Design of Microwave Filters Formed by Asymmetric Broadside-co upled CPW Using S-parameters

非对称支持宽边耦合共面波导可看作是非均匀介质中的非对称耦合传输线 ,文中在非均匀介质中的非对称耦合传输线散射参数的基础上 ,推导出非对称宽边耦合共面波导的散射参数。利用所得散射参数研制了非对称支持宽边耦合共面波导滤波器 ,试验结果表明采用散射参数进行电路分析和设计的有效性。设计研制了f =3～ 5GH z的带阻滤波器 ,采用微波复合介质板 (εr=9.6、厚度为 0 .8m m) ,底层填充介质为聚四氟乙烯材料(εr=2 .1) ,上层为空气 ,上、下宽边耦合共面波导的中心导带宽度为 w =3mm ,槽宽为 sg=0 .50 mm ,长为 1=12 .57mm。上、下共面波导距离屏蔽盒顶、底的高度为 h1=10 mm。引出线采用微带渐变线进行阻抗匹配。这些为非对称支持宽边耦合共面波导在三维 (多层 )

The asymmetric su pported broadside-coupled CPW (coplanar w aveguides) can be considered as the asym metric coupled transmission lines in inh omogeneous medium. In this paper, based o n the scattering parameters of the asymm etric coupled transmission lines in inho mogeneours medium, the scattering parame ters of the asymmetric supported broadsi de-coupled coplanar waveguides are deriv ed. Using the scattering parameters, the microwave filters formed by the asymmetr ic supported broadside-coupled coplanar waveguides are designed and manufactured . The experimental results indicate the validity of the s-parameters in the anal ysis and design of the circuits. The ban dstop filter from 3 GHz to 5 GHz is manu factured on the microwave composite diel ectric plate (ε r=9.6 and the thicknes s=0.8 mm), the filled dielectric materia l in the lower layer is PTFE (ε r=2.1) . The filled dielectric material in the upper layer is air. The center conductor width of broadside-coupled CPW is 3 mm, slot is 0.50 mm, length is 12.57 mm. The top and bo ttom metallic covering plates are positi oned at the distance 10 mm from the surf ace of the dielectric plate, respectivel y. The gradual change microstrips are us ed to match the impedance of input and o utput port. The theoretical work and pra ctical experience have laid the solid fo undation for the application of the asym metric supported broadside-coupled copla nar waveguides in the three dimensional (multilayer) microwave integrated circui ts.