# radiation box dimensions in HFSS for a CPW structure

1. ## radiation box dimensions in HFSS for a CPW structure

hi guys

i used to work on printed monopole antenna with microstrip line fed. in such antenna the radiation box dimentions is lamda/4 from each surface of the antenna except the one that port is there.

i want to know if it is the same in CPW fed antenna or not?

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2. ## Re: radiation box dimensions in HFSS for a CPW structure

Hello

lambda/4 is the minimum dimension you are supposed to have. it is better to have a dimension larger than quarter of a lambda in every direction and especially in the direction of radiation. you can use wave port and have a rectanglular pec on top of the port to have the wave port inside the radiation box solved or use lumped port.

i ask you to have have a radiation box away frm the port because then you get a better understanding of the effect of the line of the radiation characteristics.

Hope that Helps

Regards
Rotmanlens

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3. ## Re: radiation box dimensions in HFSS for a CPW structure

dear Rotmanlens

thanks for the ur help and it's useful

i have another question about CPW and lump port. i'm trying to simulate a slot antenna with CPW fed. i want to know how i can use lump port or wave port. i plotted this structure and used lump port :

i want to know if it's right or not. and also if the size of lump port's plane is important or not.
thanks a lot

4. ## Re: radiation box dimensions in HFSS for a CPW structure

Yes

Lump port or waveport are the sources, they have to be between your ground and the actual source in the design. yes the plane of the lump port is very important because it dictates the source.

Regards
Rotmanlens

5. ## Re: radiation box dimensions in HFSS for a CPW structure

dear Rotmanlens

u mean that the size of lamp port's plane is important. ( yellow plane in the photo )

so how can i find the proper size?

thanks a lot

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6. ## Re: radiation box dimensions in HFSS for a CPW structure

Opamp

Why don't you post your file here,its more easier answering your question,and probably i can make the necessary corrections to it and post it back here.from the picture i am unable to figure out properly

Regards
Rotmanlens

7. ## Re: radiation box dimensions in HFSS for a CPW structure

dear Rotmanlens

i attached my HFSS work here but i had to change the extension to a text file. if u couldn't open it, change txt to hfss.
thank u my friend

8. ## Re: radiation box dimensions in HFSS for a CPW structure

Hi Opamp

Everything looks fine, just check your radiation boundary, it is way too huge which will slow down the simulation time.

Regards
Rotmanlens

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9. ## Re: radiation box dimensions in HFSS for a CPW structure

hi Rotmanlens

oh yeah u r right man.my mistake i just found out that my radiation box is 4 times bigger.thank u

Rotmanlens do u know the diffidence between grounded CPW and ungrounded CPW? and also can i use wave port instead of lump port in this structure?

10. ## Re: radiation box dimensions in HFSS for a CPW structure

No worries.

Yes you can use waveport in this structure with a PEC cap on top of it,since hfss does solve inside so a waveport inside the radiation box yields you an error. so put a PEC cap on top of the waveport.

No i havent really worked with a CPW prior to this one.But if you have any literature pertaining to your question i should be able to help you out or i will have to refer to my text book

Regards
Rotmanlens.

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11. ## Re: radiation box dimensions in HFSS for a CPW structure

Originally Posted by rotmanlens
No worries.

Yes you can use waveport in this structure with a PEC cap on top of it,since hfss does solve inside so a waveport inside the radiation box yields you an error. so put a PEC cap on top of the waveport.

No i havent really worked with a CPW prior to this one.But if you have any literature pertaining to your question i should be able to help you out or i will have to refer to my text book

Regards
Rotmanlens.
Dear Rotmanlens,
Thanks for your notes, that was really helpful as I am trying to design CPW as well.
I have a question about the PEC cap. I am using a PEC rectangular wave port, so what are the dimensions of that PEC cap layer? is it rectangular and is it Okay to use a PEC rectangular wave port in my design or it should be metal instead?

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