excitation and pec cap in hfss

[prateek3790]

suppose i made a structure assigned wave port to it now suppose if the whole geometry is kept inside the radiation box such that the port is also inside.(using hfss)

1. will that be called internal excitation?
2. in order to use wave port without making any change in the radiation box do i need to use pec cap on one side of the wave port. how to decide the pec cap dimension?
3. if the radiation box is adjusted such that it does not enclose the port but is in the same plane as the port then is it external excitation? do i need to use the pec cap for this case as well.if i have used lumped ports ?

4. if i assign lumped ports instead of wave port then irrespective of the excitation there is no need to use any pec cap.

 

[mnhasant]

Hi,
It looks like my problem and your problem are same. In fact I was going to start a thread about "internal waveport & PEC cap in HFSS" but as I saw your post, I thought it would be good to discuss here.

To answer some of your questions:
1) Yes, in this case it is internal waveport since it lies inside radiation box and simulation will not run. It will generate error message with red cross bubble. Therefore, I always adopt a technique while I have waveport in my antenna. I always restrict radiation box's boundary in the same plane in which plane waveport face lies.

2) I do not know what is PEC cap.
In one of my designs of planar antenna, I thought to use "wave port" inside radiation box and HFSS gives error message
If an internal wave port is desired,
please add a PEC cap to one side of the port surface.
(12:57:12 PM Dec 20, 2016)

Could you please tell me what is PEC cap? cap means what in this context?

3) No, for lumped port you do not need PEC cap fortunately.

4) Irrespective of the excitation, lumped port does not need PEC cap.

I am attaching some snap shots of lumped port vs waveport. Take a look. and please tell me more about PEC cap. I know nothing about it

 

[prateek3790]

when you are using wave port internally you need to make a small solid of approx same size assign pec to it and place it in the back of the wave port. you can refer to these threads
1. https://www.edaboard.com/threads/96995/
2. https://www.edaboard.com/threads/142827/

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also can you tell me what is the difference between these two examples @ page 1.2-12. why in the first example there is no need to attach a uniform cross section like they did in the second example.

http://anlage.umd.edu/HFSSv10UserGuide.pdf

 

[mnhasant]

Hi, thanks for your help about PEC cap.
I did not understand your page notation. Would you again tell me your concerned page in that pdf doc file?

 

[prateek3790]

page no 73 of the document

 

[mnhasant]

It is because "Port can only be defined on uniform continuity of cross section" No tapered face allowed for wave port definition.
I explained in the attached figure below with marking. check it plz.

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I made a rough diagram of PEC cap attached to the port (pink color).

Could you plz take a look and tell me if I correctly understood the PEC cap placement to the port? Is my understanding correct ?


I desperately need to know PEC cap defining because my current project requires two antennas placed inside radiation box with PML boundaries. Since I have to define "internal wave port" (located inside radiation box), I must know how to add PEC cap on port.
Please help me

 

[mnhasant]

Oh I solved my problem about internal waveport with PEC cap. Thanks to google image search