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How to obtain proper s-parameter values for defected ground structure (DGS)

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btv_murthy

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Dear sir,
I designed one defected ground structure (DGS) for microstrip as in the one of the IEEE paper,am not getting proper graph as shown in the IEEE paper and dgs simulated using MWO software. Here with I am attaching the EM structure and also related document. Can u anybody help me to get the proper graph as shown in the IEEE paper.
 

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  • DGS_MICROSTRIP FILE.jpg
    DGS_MICROSTRIP FILE.jpg
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  • Dgs_IEEE_document.pdf
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I don't know if you set correctly the parameters of the dielectric substrate in MWO (as Height, Er, Loss, etc), but for sure you have a problem with the ground plane design that you did. There is a cut in the metal plane (left side, parallel with the TL) that will affect the DGS parameters.
 
vfone said:
but for sure you have a problem with the ground plane design that you did. There is a cut in the metal plane (left side, parallel with the TL) that will affect the DGS parameters.
Click to expand...

I think the cut is fine, if it is zero width. This it is from a self-intersecting polygon required to create the cutout (GDSII style cutout for layout tools that have no anti-metal).
 
vfone sir
I have taken height as H=1.58, loss =0.001, thickness of conductor =0.0356, relative permitivity =4.4, characterstic imedence =50 Ohm,you are telling about the parallel TL , that I can't remove it
 
volker_muehlhaus said:
From your paper:

"The substrate with 62-mil thick and a dielectric constant of ten was used for all simulations"
Click to expand...

Dear Volker Sir,
I am sorry, have wrong specification in the previous post. The following specification are used for creating DGS

relative permitivity = 2.2,
loss tangent = 0.02
characterstic impedance =50 Ohm
operating frequency =3GHz
electrical length = 90 DEGREE
height of substrate = 0.7874mm= 31mil
thickness of conductor = 0.036mm
Using the transmission line calculator I got the following values
L =18.2275mm
W =2.37934mm
Then I rounded L and W as 18mm and 3mm. I have drawn DGS using above values.
 
volker_muehlhaus said:
From your paper:

"The substrate with 62-mil thick and a dielectric constant of ten was used for all simulations"
Click to expand...
Volker Sir,
I am sorry , have given wrong specifications. The following specification are used for creating DGS
relative permitivity = 2.2
loss tangent =0.02
characterstic impedance =50 Ohm
operating frequency =3GHz
electrical length =90 degree
Heigth of substrate (H) =0.7874mm =31mil
thickness of conductor =0.036 mm
Then I got the following values calculated using TL calculator
L = 18.2275mm
W = 2.37034mm
I rounded L and W values as 18mm and 3mm.
 
hi,how do design rat race coupler by using dgs,how to find the parameters(a,b,g),can any one give the details of it???
 

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