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result is diffirent if frequency range is diffirent in CST Microwave Studio?

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leesixan

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result is different if frequency range is different in CST Microwave Studio?

Hello.
I design a antenna by CST Microwave Studio. And I have a problem.
My result is different if my frequency range is different :sad:.
eg:
If frequency range is: 1-3.5 (GHz). Result is "beautiful".
If frequency range is: 1-3 (GHz). Result is so bad.
My project View attachment full patch.rar
Please help me.
Thanks for read topic
 

Darktrax

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This is likely to be a inadvertent simulation mistake. If you simulate over (say) 0.5GHz thru 4GHz, you should see the region where the antenna works in the middle, and the regions where the device is no longer resonant.

if you used a separate instance to simulate the second (1-3 GHz) check that you got the units correct. Maybe you inadvertently had it set to MHz instead of GHz.. or you had a boundary symmetry different, or some little thing like that.

- - - Updated - - -

I was able to check with a clever colleague. There is no mistake. Both frequency ranges give the same result.
Mismatch is about S11= -0.5dB from 1.5Ghz to 2.7GHz. The resonance is at about 3.14 GHz where S11 is about -5dB (poor).
The 3Ghz curve follows the 3.5Ghz curve, but of course, the resonance is beyond its range.
 

leesixan

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This is likely to be a inadvertent simulation mistake. If you simulate over (say) 0.5GHz thru 4GHz, you should see the region where the antenna works in the middle, and the regions where the device is no longer resonant.

if you used a separate instance to simulate the second (1-3 GHz) check that you got the units correct. Maybe you inadvertently had it set to MHz instead of GHz.. or you had a boundary symmetry different, or some little thing like that.

- - - Updated - - -
I was able to check with a clever colleague. There is no mistake. Both frequency ranges give the same result.
Mismatch is about S11= -0.5dB from 1.5Ghz to 2.7GHz. The resonance is at about 3.14 GHz where S11 is about -5dB (poor).
The 3Ghz curve follows the 3.5Ghz curve, but of course, the resonance is beyond its range.

Dear Darktrax
First, thanks so much for giving your time.
I use Transient Solver.
Case 1: frequency range: 1-3.5GHz.
This is my result: frequency range 1 to 3.5GHz.jpg
Case 2: frequency range: 2-4GHz
This is my result: frequency range 2 to 4 GHz.jpg
S-Parameter in 2 case is very different.
What result I can trust more?
"There is no mistake. Both frequency ranges give the same result". Can U up your result. Because i can't understand where i'm wrong.
 

johnjoe

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Did you used automatic mesh refinement?
 

Intikhab

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What about the phase of S-parameter?


This is likely to be a inadvertent simulation mistake. If you simulate over (say) 0.5GHz thru 4GHz, you should see the region where the antenna works in the middle, and the regions where the device is no longer resonant.

if you used a separate instance to simulate the second (1-3 GHz) check that you got the units correct. Maybe you inadvertently had it set to MHz instead of GHz.. or you had a boundary symmetry different, or some little thing like that.

- - - Updated - - -

I was able to check with a clever colleague. There is no mistake. Both frequency ranges give the same result.
Mismatch is about S11= -0.5dB from 1.5Ghz to 2.7GHz. The resonance is at about 3.14 GHz where S11 is about -5dB (poor).
The 3Ghz curve follows the 3.5Ghz curve, but of course, the resonance is beyond its range.
 

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