HFSS and paper antenna design mismatch

[myazdi83]

Hi to all
Very good discussion, Ilearned many interesting trips. The waveport definition is fantastic!
be happy.

---------- Post added at 06:50 ---------- Previous post was at 06:45 ----------

hi Okta
I am familiar with CST. In CST the air box is not needed to be defined. You should just select the template as planar microstrip antenna.

 

[sweetchoto]

@Okta..

I will try to do it with lumped port aswell. I am quite busy these days but i ll post the results and file as soon as i ll do it with lumped port. But results ll be the same

/SC

 

[OkTa]

Hi to all,
@sweetchoto: Thanks for grate helping . I understand lumped port and wave port results same but I wonder where is my problem in lumped port simulation. I am new in HFSS and I learn very much in this discussion so if you post your design file I will learn lots of thing about them .

 

[sweetchoto]

Hi to all,
@sweetchoto: Thanks for grate helping . I understand lumped port and wave port results same but I wonder where is my problem in lumped port simulation. I am new in HFSS and I learn very much in this discussion so if you post your design file I will learn lots of thing about them .

hi Okta,

I do not define the integration line because you define integration line when you want to look for the multiple modes,because the orientation of electric field differs from mode to mode. If you are interested in looking for more modes at the port then you have to define integration lines for each mode separately. But there is no need to do it in your case. That is the reason i did not define any integration line at first.

But even if you deinfe the interation line from the bottom of waveport to the top the results ll be the same as you can see in the attached file. Do not forget to look at the 'Port Field Display' option in Project manager window,when u will click on it it will show you the orientation of Electric field lines on the port. You will clearly see that only one mode is propagating. Compare this orientation of electric field lines with that which you have got from the file in which i havnt defined the integration line and you will find no difference. It means integration line is not needed to be defined in this case.

For further information on integration line, click the 'Help' and then 'search' button and type it in there,you will get alot of knowledge/information from there. dont ignore help/search button. always try to get help from HFSS first.

Hope it helps.
/SC

 

[OkTa]

Thanks alot This knowledges very helpful for me.
I have a one question if I use copper box instead of copper sheet, does it cause big change in simulation? and in box situation am I define boundary condition?

 

[sweetchoto]

Hi Okta,

I now understand that what was your question. I downloaded your new file,Tell me why you are using BOX instead of Copper sheet????? In reality there will be sheet of copper on top of substrate not a BOX. How do you say that your modeled antenna structure is more closer to Reality????

 

[OkTa]

Hi sweetchoto,
I simulate with copper box and results same . I think in reality we use not a sheet of course approximately sheet but I think the box is very thin 0.1mm in my design. In reality we use copper it has height this is my key idea. if we use sheet instead of box , is this an approximation or false modelled?
Also lumped port problem still I do not understand

 

[sweetchoto]

Hi sweetchoto,
I simulate with copper box and results same . I think in reality we use not a sheet of course approximately sheet but I think the box is very thin 0.1mm in my design. In reality we use copper it has height this is my key idea. if we use sheet instead of box , is this an approximation or false modelled?
Also lumped port problem still I do not understand

I have simulated with lumped port. See the attached file. In reality height of copper sheet is negligible and you can perfectly model it with a copper sheet,it will not change the results. Anyways,if you want to use BOX with negligible thickness as you have specified,do not forget to assign 'Copper' material instead of 'PEC' as 3D objects can be assigned materials whereas for 2D objects/sheet you cant assign material in HFSS. Always use materials to make your simulted results as close as possible to your real results. That is the reason i have used 'Finite Conductivity' for all the 2D objects in my file instead of assigning 'PEC' to them.
Hope so everything is clear now. Have fun and tc.
/SC

 

[OkTa]

Thanks for all support I understand many things I didn't find any difference with lumped port with my simulation except copper-pec and box-sheet thing. Probably this cause. Lumped port and wave port solutions are slightly different it seems normal.
If I desing probe feed I have two questions;
1. what is the size of outer and inner conductor of coax? I think such as txline editor estimate radius according to substrate to match 50 ohm. But length of probe is user defined what is the length of probe also?
2.In analysis, we put probe in airbox with wave port with cap or we use lumped port to excite it?

 

[sweetchoto]

1- If you are asking about Co-axial cable then determine the dimensions of inner and outer conductor radii through equations which you can find in any microwave book or on internet. The length of coaxial doesnt make any difference except the phase shift which ll not effect the results here. The normal/sensible length should be 1 wavelength.

2- Put it inside Airbox and excite it with WAVEPORT. And now you should know that when WAVEPORT is inside airbox how to make it work in HFSS.

/SC

 

[OkTa]

Thanks a lot sweetchoto for helping. Your help very supportive to understand simulation in HFSS. I will try probe fed. if I am in trouble with probe, I am asking you again. Thanks

 

[OkTa]

Hi all;

I matched S11 in paper and hfss simulation with the aid of sweetchoto. But I have problems with radiation pattern. When I draw pattern in xy xz yz plane in hfss, they have different cros-pol amplitude I do not understand why. So Shape of pattern like in paper but cros pol component have bigger amplitude than co pol component according to paper. air box lamda/3 far away every radiation surface, resonanat freq 2.45Ghz and 5.75Ghz and max mesh length over air box 12.5 mm, Can mesh length cause this situation? or Where I made an error?

please Anyone help me?

thanks

 

[noor_awad]

to sweetchoto
i have HFSS version 11
and ur file doesn't open with me
maybe different versions
could u please attach files with version 11 to know how to make waveport cap
please sir
and thanks alot

 

[ziedbfz]

hi ,
first of all , sorry for my english because
i realised a triangular patch antenna that resonnate in 2.45 GHz , but with using of waveport or lumped port , S-parameter are shifted to 4.45 GHz.
when i use lumped port with the same dimmenssion of micrstrip line , the s-param is located at 2.45 Ghz.
so i would to ask how to resolve this problem ?
thanks

 

[bijus]

Hi sweetchoto,
i am a beginner in HFSS and very much interested to study the design and details shared by you. But unfortunately i am using HFSS version 11. So i am not able to open the links that you have shared. So please share the details suitable for version 11. Sorry for disturbing you sir, but it will help very much the people like me who where intrested in this field.

Thanks & regards,

Biju