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CST simulation circular polarization

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laura1282

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Hi,

I want to simulate a patch antenna using 2 excitation signals with 90 degree phase shift to achieve the circular polarization purpose.
I have read the relevent posts on the forum, however, there is no post mentioned where to add another signal and how to define the 90 degree phase shift. When I add new excitation signal, I can only choose the frequency range..Don't know where to change the phase.

PLease dont ask me read the CST example under $%^&folder..Because I don't have them due to some reasons.

I'm new to CST MW..PLease help me!!Thank you!!!!
 

laura1282

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Anyone helps???
I wil appcreciate very much~~~~~~~~~~
 

budder8818

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If you figure this out please PM me

---------- Post added at 17:09 ---------- Previous post was at 16:48 ----------

I think it might have something to do with the distance that the two waveguide ports are seperated by. i.e. the delay should be 90 out of phase with each other. In addition, one input should be vertically TE and the other Horizontally TM. Please correct me on the TE and TM stuff.
 

laura1282

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Hi budder8818,
I think I didn't clarify this clearly. The patch antenna I simulated has only one input port. The excitation signal is transmitted into this port and then radiated by the patch into the air. Now I need to add two signals simultaneously which have the same amplitude and are 90 degree out of phase. But how to produce the signals with 90 degree phase shift? Or do I have to write the code of a circularly polarized signal and then import into the CST microwave studio? And in what language?
I am very blur about this....
Thank you for help~
 

Aleksej

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Hi everyone!
I'm not sure 'cause I never worked with it but I think it must be impossible to stimulate the port with two signals in quadrature in a transient solver simulation since the input signals can't be everlasting sinusoids.
By the way, when you set farfield monitors and simulate your structure, you should find, in the folder containing the farfields results, two files in which the anthenna pattern is reported relatively to the left circular polarized part of the farfield and to the right one respectively.
Is it what you were looking for?
 

laura1282

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Hi everyone!
I'm not sure 'cause I never worked with it but I think it must be impossible to stimulate the port with two signals in quadrature in a transient solver simulation since the input signals can't be everlasting sinusoids.
By the way, when you set farfield monitors and simulate your structure, you should find, in the folder containing the farfields results, two files in which the anthenna pattern is reported relatively to the left circular polarized part of the farfield and to the right one respectively.
Is it what you were looking for?

Hi Aleksej,

Thank you for reply. I understand that already. The port should be simulated by one signal only regardless of the phase. As long as the antenna is circularly polarized (which is decided by its structure), the output signal will be circularly polarized. Am I right?:smile:
However, another problem is, I checked the left circular polarization and right circular polarization in the navigation tree, their gains are very similar. i.e. The gain of right hand polarization is only 1 dB higher than the gain of left hand polarization. So can I say my microstrip antenna is right hand circularly polarized?
If not, how should I adjust the antenna to achieve the right hand polarization? For example, adjust the probe feed position or the truncation area but how? Since RHCP is required.

Thanks~~~~~~
laura1282
 

Aleksej

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I suppose that the Farfield is given by the superposition of the left circular polarized part and the right one.
Thus, if the two parts show the same value the resulting polarization is linear.
If these preliminary remarks aren't wrong you should modify your structure as long as the left hand polarization is not sufficiently rejected.
For what about the levers you can use to achieve the results you need, I think that if I were in you I would study the theoretical principles which could allow the specific structure you use to radiate just the right hand polarization before changing details in order to see the way its behaviour reacts to these modifications.
Excuse me if my English is not good as my Italian.
 

abdoeng

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try to use microstrip hyprid coupler,it has 4 ports
1- input port
2- output port with no phase shift
3-output port with phase 90 than port 2
4- matched load
regards
 
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