pec reflection
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]
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 ?
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
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
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
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
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
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
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
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
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
adboeng do you have again the dra model for CST ?
what is dra model piboo??
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 ?
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
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
up ?
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
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
that method above caculate the phase versus frewency not dimensions as WG
regards