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shahnazyasir
Joined: 08 Aug 2007
Posts: 8
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 16 Sep 2008 7:11 FSS in cst mw studio |
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Hi
i am simulating fss in cst mw studio. First i am using the example discussed in PDF document "frequency selective surfaces " by REmsky in which we have an annular ring on a dielectric substrate . They have simulated it with hfss and got minimum transmission coefficient at almost 9 Ghz but i am getting it at near6 Ghz. i dont know why
What i am doing is , i am taking plane wave with e vector in x direction and boundary conditions with x as perfect electric, y perfect magnetic , zmax as open and zmin as electric. am i doing right
please help me
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piboo
Joined: 06 Feb 2008
Posts: 64
Helped: 1
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| 16 Sep 2008 9:13 FSS in cst mw studio |
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Hi shahnazyasir,
1/I think you must try to use a waveguide port instead of a plane wave:
You use PEC and PMC boundaries conditions, this choice is due to have the electric and magnetic field orthogonal so it's a good choice when you use a waveguide port.
But in the case of the plane wave E and H are already orthogonal so you don't need to use this boundaries conditions. For plane wave you must use periodic conditions to have an infinite structure.
2/ If you use a plane wave like this you don't have any reference of the incident field and reflected. There is a macro to simulate phase reflexion of a FSS / EBG / HIS etc...
If you use a waveguide port with PEC and PMC conditions and you put the reference's port to the surface of your structure, CST will simulate S-Parameter and you will have magnitude and phase reflexion of your structure.
Hope you will understand and help you,
Regards
Piboo
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shahnazyasir
Joined: 08 Aug 2007
Posts: 8
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| 17 Sep 2008 8:09 Re: FSS in cst mw studio |
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actually i want to simulate a subreflector which is reflective for infrared and transperant for ka band and it will be in far field of horn antenna thats why i am using plane wave simulation , i am trying to get frequency response by using probe. if its correct way to get frequency response
and also can anybody guide for the design of fss at infrared
thanks
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piboo
Joined: 06 Feb 2008
Posts: 64
Helped: 1
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| 17 Sep 2008 8:59 FSS in cst mw studio |
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You want to determine the reflected field by your surface.
As I explain before, by using plane wave and probe, you need to do 3 simulations: you need to simulate the field in free space, on a pec and finally in your structure.
Then a macro calculate the reflected field by your surface.
If you just do the simulation with a probe and plane wave sending on your surface you will not have the reflected field: you will also have the incident field in the response. You can check it in cst by viewing the signal.
You can use the other method with a waveguide port which is really faster.
And for the design of a fss at infrared I can't help you but maybe look the Munk's book: "Frequency Selective Surface: Theory and Design"
regards
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shahnazyasir
Joined: 08 Aug 2007
Posts: 8
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| 17 Sep 2008 14:39 Re: FSS in cst mw studio |
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actually i want to simulate a subreflector which is reflective for infrared and transperant for ka band and it will be in far field of horn antenna thats why i am using plane wave simulation , i am trying to get frequency response by using probe. if its correct way to get frequency response
and also can anybody guide for the design of fss at infrared
thanks
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shahnazyasir
Joined: 08 Aug 2007
Posts: 8
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| 18 Sep 2008 7:07 Re: FSS in cst mw studio |
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Sorry same post was sent again by mistake, i will try to simulate with waveguide and hoping that ,will get some results
thanks
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shahnazyasir
Joined: 08 Aug 2007
Posts: 8
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| 22 Sep 2008 12:51 Re: FSS in cst mw studio |
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Hi Piboo:
Thanks for your kind help. I am still confused a bit. i am using CStMWS version 4. I have read in this forum that i should define an embeded port but there is no option availabe for this , so kindly can you tell me how to define a waveguide port. May be it seems very easy question but please i am a new user of cst
Thanks
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piboo
Joined: 06 Feb 2008
Posts: 64
Helped: 1
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| 23 Sep 2008 9:57 FSS in cst mw studio |
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Hi shahnazyasir,
I had never used CST v4 so I don't think how I can help you...
But since the version 2006 (the first I have used) you have an option to fix the reference plane to the surface of your structure.
You can find in this forum a topic about plotting phase reflexion using a wavguide port.
regards
piboo
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prafuldeo
Joined: 26 Mar 2008
Posts: 78
Helped: 2
Location: UK
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| 25 Sep 2008 15:48 Re: FSS in cst mw studio |
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Dear shahnazyasir,
When you define the waveguide port there are two fields Zpos and Distance to reference plane .. so fill it and see if u get the desired results..
Praful
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shahnazyasir
Joined: 08 Aug 2007
Posts: 8
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| 26 Sep 2008 7:09 Re: FSS in cst mw studio |
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hello:
i am sending the model of my example with results, i am using the example explanied at page 19 of the pdf docment attached here. i am not getting the same results , please do tell me where i am making mistake.
While defining wavegudie port, when i give zpos at the surface of structure i.e. .66mm this error come , waveguide for port 1 is too short. please explain me why this occurs and how much much should be the dist to refrence plane?
With regrds
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abdoeng
Joined: 22 Feb 2004
Posts: 602
Helped: 10
Location: EGYPT
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| 28 Sep 2008 5:02 FSS in cst mw studio |
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aslamo alykom shahinaz,see that link,it may help u
http://www.edaboard.com/viewtopic.php?t=262936&highlight=abdoeng
Added after 39 seconds:
also see that one
http://www.edaboard.com/viewtopic.php?t=304618&highlight=abdoeng
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