具有交叉阴影接地平面的微带迹线阻抗如何设置

所有，我有一个由聚酰亚胺制成的柔性电路（er = 3.3到3.5），我想用ADS2011布局确认单端微带线和差分偶数/奇数模式走线的阻抗。
我已将Gerber文件加载到工具中，我可以设置多个端口。
我的目标是在存在交叉阴影平面（非实心）的情况下提取单端/差分阻抗。
柔性电路在动态环境中使用，并且它不能是实心平面参考，因为它会使其疲劳，并最终随着时间的推移而失效（裂纹迹线等）。
我想调整走线和交叉影线参数以达到90欧姆差分阻抗和50欧姆单端。
我将在两种情况下分解问题 - 差分和单端。
我想为差分设置一个案例，并为偶数和奇数模式提取迹线的阻抗。
我相信这在ADS中是小菜一碟，我只是不知道如何设置它。
我知道我可以转换阻抗Z11 = 50 *（1 + S（1,1））/（1-S（1,1））。
从这里我如何得到奇数和偶数模式？
如何对交叉影线进行参数化，以便我可以改变一些参数并查看阻抗变化？
我真的很感激任何帮助。
我挖了我的旧书，我重新找到偶数= Z11 / 2 odd = 2 * Z11的阻抗。
但是，我只需要知道我需要在跟踪上放置多少个端口。
对于差分情况，我想这是一个双端口测量，但是地面参考怎么样？
我会把以下端口P1，P2分别对一端进行差分对。
P3，P4到另一端，地面怎么样？
它只是P5吗？
然后我将其导出到原理图，并添加地面，因为我无法在布局中添加地面？
任何帮助将不胜感激。
这是我通过实验和FCC测试得到的经典案例，但我没有模拟模型来预测这一点而不需要迭代flex。
谢谢rjrodrig



     以下为原文

  All,

I have a Flex circuit made out of Polyimide (er =3.3 to 3.5), I want to confirm the impedance of single ended microstrip and differential even/odd mode traces using ADS2011 Layout.  I have loaded the Gerber files into the tool, and I can setup multiple ports.  My goal is to extract the single ended/diff impedance in the presence of a cross-hatched plane (not solid).  The flex circuit is used in a dynamic environment, and it cannot be a solid plane reference as it will fatigue it, and eventually fail over time (cracked traces etc).  I want to adjust the traces, and cross-hatch parameters to hit 90 ohms differential impedance, and 50 ohms single ended.

I will split the problem in two cases -- the differential and single ended.  I want to setup a case for the differential, and extract the impedance of the traces for even and odd mode.  I am sure this is a piece of cake in ADS, I just don't know how to set it up.  I know I can convert the impedance Z11 = 50*(1+S(1,1))/(1-S(1,1)).  From here how do I get odd and even mode?  How do I parametrize the cross hatch so I can vary the some parameters and look at the impedance changes?

I would really appreciate it any help.  I have dug up my old books and I recapped the impedance for even=Z11/2 odd=2*Z11.   However, I just need to know how many ports I need to put on my traces. For the differential case, I imagine this is a two port measurement, but what about the ground reference?  I would put the following ports P1,P2 to diff pair one end. P3,P4 to the other end, what about ground? Is it just P5?  Do I then export this to schematic, and add ground since I can't add ground in Layout?

Any help would be greatly appreciated.  This is a classical case I have gotten around experimentally and through FCC testing, but I don't have a simulation model to predict this without iterating the flex.

Thanks
rjrodrig