[SOLVED] impedance line calculation

[guytoub]

hello !
i wanted to know how i can calculate the impedance on a microstrip line as below.
it's consist of a ground plane , an air dielectric above the Gnd, a substrate with its Er above the air substrate and finally the line.
i can't find the formula for it .

thanks

 

[KlausST]

Hi,

there are online calculators ...

Klaus

 

[guytoub]

I found many calculator but they only calculate for one substrate . For exemple on everething rf

 

[FvM]

There's no exact formula for this geometry. There might be a solution for the layered dielectrica problem by conformal mapping but I'd prefer a FEM solver to find capacitance per unit length. Inductance per unit length is identical with basic microstrip. This is about simplified low frequency solution. At higher frequencies, coupling with free space becomes relevant.

Notice there's a number of papers about effective dielectric constant of multilayer.

 

[guytoub]

Hello,

I found the way to calculte this type of impedance with ADS of keysight. They have a calcultor called impedance line controller.
Thanks for your help

Regards