solve inside for the metals in HFSS

[tw20053010]

Hello,
Since my microstrip line structure is working under 2GHz, I have to take skin depth effect into consideration. Therefore, I select the metal lines, and add skin depth mesh on all these metal objects. Meanwhile, I elect the inside solution for all the metal objects. Could u tell me whether my manner is right?
I find electing or not electing the inside solution for the metals will lead different simulated results. So could u tell in what case should I elect the insde solution for metal?

Thanks a lot!!!!!!!!!!!!!!!!!!

 

[jlovejoy]

I have this same issue in some models I am working with. The simple answer is when the microstrip line thickness or width is less than 5 skin depths then skin depth loss should be included. In HFSS this means check the solve inside box for the respective line or ground plane. This really applies to any metallic object in the sim that is less than 5 skin depths.

I read a paper on this a year or so ago but could not find a link to it. You can see the effect in HFSS by simulating a simple microstrip and doing a frequency sweep that will pass through the 5 skin depth region. The characteristic impedance should look like a decaying exponential.

Standard Wheeler equations for characteristic impedance don't take this into account. However, as the line thickness goes above 5 skin depths, it should approach the Wheeler calculations. There is an addition to the WHeeler equation that will take this into account but I have not played with it.

Hope this helps,

Jim

Added after 1 minutes:

Whoops, I just realized how old the original post is. Sorry.