Pls help how to set the mesh size & stimulate port in HF

[Rosina]

Hello,all:
I newly designed an antena , the simulation result seems unreasonable.
I try to modify diffrent mesh size and do the simulation, but the result is always the same one.
There may be some problem in the way of setting mesh size and stimulate port(I used wave port).
my problem is :
1. how to set the mesh size.
2. how to set stimulate port.
thanks inadvance.

 

[Ankesh Garg]

Re: Pls help how to set the mesh size & stimulate port i

Mesh Size: HFSS generates mesh according the solution frequency provided in the analysis setup, now generally for bandpass structures the solution frequency is given as the center frequency otherwise it is given as the highest frequency form the sweep range and if the solution converges then the results can be relied on, but there may be certain parts in the structures for example near ports that you can refine your mesh.

Port: wave ports are generally used when you know exactly the characteristic of the wave port(HFSS asumes it to be coming from an infinitely long waveguide whose cross section is same as that of the sheet given and calculates the S parameters with respect to that value, in this case you can run a ports only analysis to know about the wave port that you have used to know about the characteristic impedance of the port). Also wave ports are defined at the outer boundary interface. On the other hand lumped ports are used inside the air box and can be assigned the characteristic impedance (50ohm etc), so wave port or lumped port of same characteristic impedance should give same results.

Be sure that the convergence has taken place and all the boundary conditions are correct. If you are not comfortable with wave port you can use 50ohm lumped port. With wave port be sure to know about the characteristic of the wave port that yo have used.

Hope this helps

Regards
-Ankesh

 

[kaandee]

Re: Pls help how to set the mesh size & stimulate port i

Hi Ankesh
I have designed two arm archimedean spiral antenna using CST. The results look resonable. But when i increase no of antenna i mean to get arrat antenna, i couldn't simulate. because no of mesh cells increase. But my software is licenced one and i can use upto 100 000 cells.
Is there are any way to reduce no of mesh cells in CST if it have array antenna?

plz help me to reduce the mesh cells

thank you