HFSS EigenMode Unit Cell: Problem on Results

[JohnFid]

Hello,
I am trying to implement a bandgap diagram on a unit cell strurcture using Master/Slave Boundaries on y axis and Perfect H on x axis. On the top, there is a PML Boundary. The result diagram is shown below:



Can anyone tell me why this happen from 0 to 40 degrees?
Are the settings of the PML responsible for this?
Thank you...

 

[CG0210794]

I have done bandgap diagrams, with hfss and other methods, and I am not sure why you are using a PML. A PML is only required when you are solving a scattering problem.

 

[JohnFid]

I have done bandgap diagrams, with hfss and other methods, and I am not sure why you are using a PML. A PML is only required when you are solving a scattering problem.

I follow instructions from a paper and he uses a pml boundary for this purpose. Do you think that PML cause the problem? Is there any specific instruction to complete PML wizards settings? I also have a warning that says that the ground doesn't touch any radiation surface. I used a plane with perfect E and infinite ground plane setting checked.
Thank you..

 

[CG0210794]

Can you point me towards to the paper, so I can see what they are doing.

 

[JohnFid]

Wideband Circuit Model for Planar EBG Structures. Baharak Mohajer-Iravani, Member, IEEE, and Omar M. Ramahi, Fellow, IEEE.

 

[pkg]

Dear Sir,

i design patch antenna at 2.4 GHz.please check my design.
thank you sir.

 

[JohnFid]

Your design has 'Driven Modal' solution type, mine is eigenmode and it is a little bit differenet.
No port, different boundaries.

 

[CG0210794]

I don't think you errors are because of the PML. The wizard is pretty robust. It looks like your degree sweep, of your periodic boundaries, does not marching through the Brillouin zone correctly.

 

[JohnFid]

Dear Sir,

i design patch antenna at 2.4 GHz.please check my design.
thank you sir.

Add perfect E boundary to you patch surface.

- - - Updated - - -

Actually, I am trying to implement a different patch than this on the paper but based on the same logic:
View attachment png_2.bmp

I sweep from 0 to 180 degrees. Is this wrong? How do I find the correct sweep area?

 

[CG0210794]

Here is a really good tutorial on how to calculate a band gap diagram using HFSS.

https://www.emtalk.com/tut_2.htm

 

[JohnFid]

Actually, I am trying to implement a different patch than this on the paper but based on the same logic:
View attachment 89778

I sweep from 0 to 180 degrees. Is this wrong? How do I find the correct sweep area?

 

[pkg]

dear Sir,

dear Sir,

i got results at 2.39 GHz
minimum Return loss =-8.2 dB
minimum VSWR = 2.27.
these values is not acceptable so what should i change in this design?

 

[JohnFid]

dear Sir,

dear Sir,

i got results at 2.39 GHz
minimum Return loss =-8.2 dB
minimum VSWR = 2.27.
these values is not acceptable so what should i change in this design?

If yours antenna dimensions are not restricted, try to changed it and see what the results will be. Try to change microstrip feed dimensions.

 

[talha863]

Dear Pkg,
Kindly check your inbox
and if u still hav any query, feel free to ask me

Dear Sir,

i design patch antenna at 2.4 GHz.please check my design.
thank you sir.