Reflection Phase Diagram of PEC and PMC in CST

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prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

03 Apr 2008 20:15 pec reflection

Hello friends,
I am working with EBG designs and need to find reflection phase diagram for the same. I am using CST Studio Suite 2008 (MWS) for my simulations. I am using two methods for finding the reflection phase diagram of EBG:

a) Using macro and PEC, Open and real Unit cell model
b) Using Waveguide port and making boundary conditions as perfect E and H.

I am getting acceptable results in my simulations and both are giving nearly same results. But when I did the same with PEC and PMC, For PEC,I got 180 degree phase shift for all frequencies as expected but for PMC I am not getting 0 degree phase shift by both the methods. Does anyone knows why this so? Any help would be appritiated. Thank You

[/b]

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

06 Apr 2008 18:09 cst reflection coefficients slab

hi,

I'm also interesting by this, can you detail more the methods that you have used plz ?

Which solver did you use for "macro and pec" solution ?

abdoeng

Joined: 22 Feb 2004
Posts: 685
Helped: 14
Location: EGYPT

06 Apr 2008 21:45 pec pmc unit cell

hi prafuldeo,i already compare my results i get from cst 2008,with paper of DRA phase figure using WGA method,it give very good compatability between them
regards

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

07 Apr 2008 8:30 pec pmc

Hi piboo,
Macro method is used to calculate the reflection phase diagrams of periodic surfaces. In this we use 3 simulations of a unit cell. one with all made up of vacuum and keeping boundary conditions x,y periodic, Zmax=open add space , Zmin=open. Incident plane wave is used for excitation and probe is used for measure field and phase. Note down the phase of probe at fmin & fmax. Then simulate the second design making unit cell all PEC and change to x,y periodic, Zmax=open add space ,Zmin=electrical(Et=0). Third, simulate the unit cell with original materials and keeping boundary conditions same as second (PEC) i.e. x,y=periodic , Zmin=electrical and Zmax=open add space. Once this done, run the macro for finding reflection phase in 3rd simulation. It will ask for frequency range, phase at fmin & fmax and cst file name for PEC simulation. Fill all the parameters and you get reflection phase diagram of the test surface. you can find the macro in this forum. If not, let me know. Hope it helps.

Regards
Praful

Added after 9 minutes:

Hi abdoeng,

Could you please give me the paper title you compared your results with. I am using boundary conditions X=electrical, Y=magnetic, Z=electrical. I am taking height as Z-axis. I am getting similar results but not same. I've tried it on Samii's paper "Reflection phase characterization of EBG surfaces" and I am getting same curve but with error of ~10%. Using macro method also I am getting same error. Same with various other papers. So I am not 100% sure that I am getting correct results in CST. Have you ever tried to get reflection phase diagram of PMC? I tried to get it making Zmin=Magnetic (Ht=0) but with both the methods I am not getting 0 degree pahse. But for PEC I am getting 180 degree phase. Let me know if you have any idea. If I get 0 degree reflection phase for PMC and 180 degree for PEC. I would know that method is giving correct results. Thank you.

Praful

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

07 Apr 2008 12:32 electrical diagram - p.e.c.

thx prafuldeo,

I have a macro (which doesn't work with cst 2008) and i do the same thing as you: I simulate a vacuum structure, then with a pec structure and finally with my structure.
with periodic boundaries in ±x and in ±y. In z I have open boundaries. All with the transient solver.
Compared to the paper of Rahmat Samii, I observe a little difference too.
I don't try with a PMC structure (only with an infinite PEC).

Can you send me your PMC structure ?
I don't find the macro for reflection diagram, can you send me too ?

However, what is WGA method ?

I also would like to simulate the absorption diagram: I'm doing with unit cell in the frequency solver. Anyone have observe this ?

Thank you for your answers

Piboo

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07 Apr 2008 12:32 Ads

abdoeng

Joined: 22 Feb 2004
Posts: 685
Helped: 14
Location: EGYPT

07 Apr 2008 13:49 cst slab reflection coefficients

WGA ,method using waveguide simulation instead of periodic walls,they use 2E walls,2H walls,with lower as conductor,upperwall for TEM port

Added after 7 minutes:

WGA ,method using waveguide simulation instead of periodic walls,they use 2E walls,2H walls,with lower as conductor,upperwall for TEM port

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

07 Apr 2008 14:05 reflection phase graph

I saw you have work on dispersion diagram with cst abdoeng. I would like to know how do you plot this ?

I'm trying to simulate this diagram for a sievenpiper cell with the eigen mode.

Periodic bounds are in x and y and open for + and - z.
Plane wave is located at 13.75 from the cell.

I go in the eigen mode, (i let defaults parameters) then in parameter sweep and I choose the parameter phase to sweep from 0 to 180.

Frequency mode 1,2,3 are added in the results watch.

I don't know how to plot the results.
Moreover just like this I have a warning which said:
"The structure updates failed for at least one parameter combination. Please check the results"

But I have no results...

Can you said me where are my mistakes ?

Thank you

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

07 Apr 2008 18:14 pec color diagram

hi piboo,
I am testing a simple pec sheet and setting Zmin=magnetic to simulate PMC unit cell. but i am not getting 0 degree phase shift. for zmin=electric i m getting 180 degrees for all frequencies. You can check it with your self. I am not sure that maco is correct as it should give 0 degree for PMC

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

08 Apr 2008 9:32 cst macro

Mmh don't you think even if you make in zmin a magnetic bounds, you have already a pec material, so I don't think you can ckecked it by this no ?

Can you send me the macro plz, I don't find it in the forum

thank you

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

08 Apr 2008 13:30 cst reflection phase

Hi abdoeng,
Can you tell me the paper name by which you compared WGA method? Have you tried this method for PMC i.e making boundary condition Zmin=magnetic(Ht=0), instead of Zmin=electric(Et=0)?

Regards

abdoeng

Joined: 22 Feb 2004
Posts: 685
Helped: 14
Location: EGYPT

09 Apr 2008 18:02 pmc pec.ppt

here the paper
A Ka-Band Dielectric Resonator Antenna Reflectarray
by
M.G. Keller+, J. Shaker+, A. Petosa+, A. Ittipiboon , M. Cuhaci , Y.M.M. Antar

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

10 Apr 2008 14:36 cst pmc

adboeng do you have again the dra model for CST ?

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

11 Apr 2008 8:12 wave reflection pec

what is dra model piboo??

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

14 Apr 2008 12:27 pec and pmc boundary

The dra model is the structure presented in:

A Ka-Band Dielectric Resonator Antenna Reflectarray
by
M.G. Keller+, J. Shaker+, A. Petosa+, A. Ittipiboon , M. Cuhaci , Y.M.M. Antar

abdoeng said :

"hi prafuldeo,i already compare my results i get from cst 2008,with paper of DRA phase figure using WGA method,it give very good compatability between them
regards"

So I would like to check it too.

Can you send me your macro plz ?

abdoeng

Joined: 22 Feb 2004
Posts: 685
Helped: 14
Location: EGYPT

14 Apr 2008 12:54 phase with patch length relation in cst

hi piboo
i don't use macro file
i use waveguide model
as in paper
here the model in cst2008
any comments i am here
regards

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piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

15 Apr 2008 15:17 compare your results against the pmc method

Thank you abdoeng.

However, I don't understand these things:
1/ How can you get the curve from paper ?

2/ I can't simulate it again, why ?

How you test this method with Sievenpiper structure ?

Can you send me a macro to obtain phase reflexion diagram plz

And do you know how to get absorption diagram ?
(Absorption diagram = reflected field - incident field but its doesn't work for an infinite ground plane for me. I use a plane wave and the transient solver)

Thank you for your help

regards

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

16 Apr 2008 17:01 difference between pec and pmc

up ?

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

19 Apr 2008 8:16 diagram of reflection

Hi, here is the macro file and ppt which shows how to generate reflection phase diagram. I am having CST 2006B installed in one system, so I can get the results.

Regards
Praful

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piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

19 Apr 2008 18:23 pmc, reflected

hi thanks prafuldeo,

I have the same macro but it doesn't work on CST 2008.

Is it working for you .

PS: in the file the macro is not here but i have found in the forum the same archive with the macro

abdoeng

Joined: 22 Feb 2004
Posts: 685
Helped: 14
Location: EGYPT

19 Apr 2008 23:12 slab waveguide cst

that method above caculate the phase versus frewency not dimensions as WG
regards

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

20 Apr 2008 8:58 pec versus periodic boundary

hi piboo,
I am having CST 2006B installed in one of the lab PC so i can use this macro. Macro is embedded in top right corner of PPT. you can activate it by double click on it.
I am still not able to generate exact phase diagram as given in Samii's "Reflection phase characterization of EBG" by both macro and WGA method. I am not sure we getting correct answers by any method.

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

21 Apr 2008 10:15 phase reflection diagram wiki

hi prafuldeo,

I think you will never find the same results as Samii's paper with CST MWS: R. Samii use a FDTD method and CST use a FIT method, that's not the same. So there will always few differences between the two methods.

With the macro I obtained the same curves but the frequency of non dephasing (don't know if it's like that to translate: phase = 0°) is shifting of 1 GHz.

The best way to check it, is to do some measures Razz

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

21 Apr 2008 11:07 reflection pmc

Hi piboo,
I've attached the .cst file of samii's unit cell for 12Ghz resonating frequency. I've calculated the reflection phase by both the methods and results are also attached here. As you can see both results give fairly same results but none of them matching the original published results. If you are saying that results from FDTD is different from FIT then which one is more correct?? As you can see for original results phase crosses zero degrees around 17.2 Ghz but with my simulation around 30 degrees at 18 Ghz. I am not convinced with the results. Also can you send me the dispersion diagram settings as given in sivenpiper paper for this model?

Regards
Praful

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piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

22 Apr 2008 9:29 cst periodical boundary ppt

Hi,

I don't know which method is the best. I think a measure is the best way to check :p

I have the same results as you with CST. But if you try with a PEC or PMC you have good results.

I post the dipersion diagram in the next topic.

Also can you send me your email (in private message if you want) plz ?

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

22 Apr 2008 14:45 cst mws pmc

I've tried macro and WGA method over PEC but i was not able to check it with PMC. how did you check it with PMC??

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

24 Apr 2008 9:07 reflection characteristics of pec

To check for a PMC you can design a square pec with periodic boundaries on x and y in zmin choose PMC, zmax open/open add space

But in local mesh properties you have to uncheck the box "Consider for ..." so when you start the simulation, the pec will not be consider so you will just only have a vaccuum box with a PMC boundaries at the end.

Do you understand ?

kind regards

shahid78

Joined: 29 Jul 2006
Posts: 328
Helped: 28

24 Apr 2008 11:43 Re: Reflection Phase Diagram of PEC and PMC in CST

hi piboo
well if at the end you need vacuum box then whats the purpose of modeling PEC why not just model vaccum box and use the required boundary conditions for PMC

regards

piboo

Joined: 06 Feb 2008
Posts: 84
Helped: 2

24 Apr 2008 13:26 Reflection Phase Diagram of PEC and PMC in CST

just if you want to check for pec just after :p
no need to create another model Smile

prafuldeo

Joined: 26 Mar 2008
Posts: 153
Helped: 10
Location: UK

24 Apr 2008 15:07 Reflection Phase Diagram of PEC and PMC in CST

I did it with vacuum box. But to get phase nearly equal to zero we have to keep the thikness as low as possible. And by comparision, macro method seems to be more sensitive than WGA method