Cst help: why is small mesh step important in antenna sim. ?

[xxgcatz]

cst help

i use cst 5.0. It seems that the Small mesh step in mesh property is vey improtant in the simulation of electric large antenna. Why？
And somtimes when i simulate some atennas , there is a warning : some critical cells have expanded full size, i want to whats reanson cause that .Who can tell me , thanks a lot

 

[Pushhead]

Re: cst help

Hi,

I must disagree with you. A small mesh step is a result of your meshing setup. In other words, the way you are sampling your structure.
A better way to put it will be: As the structure contains more details, and electrically small elements - Finer meshing will help you achieve more accurate results (The cost will be a small mesh step and longer simulation time).

Regarding critical cells problem - Check out "Advanced Mesh Strategies" in CST's help documents.

Good luck,
P.

 

[xxgcatz]

cst help

So a manager has told me that the small mesh step must be setted by hand when the antenna is very large.Otherwise it will cost a lot of time!

 

[antboy]

Re: cst help

I agree with xxgcatz, but I don't know how to set small mesh by myself

 

[doug freeman]

Re: cst help

Electrically large antennas present problems for all simulation methods as they require a larger number of cells. FDTD, TLM and FIT however benefit from a linear relationship between number of cells and simulation time/memory.

With CST you can force a minimum cell size across an object, however you must keep the lamba/10 requirement for the upper frequency. Maybe you can post an image of your problem so we can see it (I don't have access to CST at the moment)

Regarding critical cells, with the PBA method sometimes the mesher will fill the cell completely with material. In order to change this you can increase the mesh density, or look at the model and see if it is actually a problem. If it is not short-circuiting any part of the model then it won't change the accuracy that much.

 

[xxgcatz]

cst help

In the mesh property small mesh step can be set handly