Author Topic: EM circular polarized wave  (Read 50279 times)

Fu-Kwun Hwang

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EM circular polarized wave
« on: October 22, 2005, 04:40:54 pm »
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The following applet show the E/B field for circular polarized wave.
The total E/B field is shown as default. You can select which component of E/B field to be shown. But do not turn on too many of them at the same time.



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Meika Resti

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Re: EM circular polarized wave
« Reply #1 on: April 27, 2010, 10:52:53 am »
Hello sir, I'm curious about how the steps to make EM circular polarized wave simulation.Would you like to show it to me?
Thank you, :)

lookang

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Re: EM circular polarized wave
« Reply #2 on: April 27, 2010, 03:04:57 pm »
Hello sir, I'm curious about how the steps to make EM circular polarized wave simulation.Would you like to show it to me?
Thank you, :)

please download the source code to examine it.
the steps are many and perhaps almost impossible to write down every step clearly.
maybe you should look at the source code and articulate your learning difficulties so that we can understand what you want to learn. :)

Meika Resti

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Re: EM circular polarized wave
« Reply #3 on: May 23, 2010, 08:08:48 pm »
Sir, I have tried to make a EM circular wave, but the magnetic field can not appear as well as the electric field. I've been trying to find fault, but I have not found it.Please help me sir...
 :'(
« Last Edit: May 23, 2010, 08:17:17 pm by Meika Resti »

Fu-Kwun Hwang

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Re: EM circular polarized wave
« Reply #4 on: May 24, 2010, 12:32:07 am »
You need to know how to create a linear polarized wave first.

Assume the wave is moving in z direction, and electric field is in x direction (which means that magnetic field is in y direction).
Then
$vec{E}=E_x sin(k z-omega t)$
$vec{B}=B_y sin(k z-omega t)$

You can download the above simulation. Double click the jar file to run it , right click the mouse and select "open EJS model" to find out how it was created in EJS environment.

Meika Resti

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Re: EM circular polarized wave
« Reply #5 on: May 24, 2010, 10:15:32 am »
I know what you mean sir, and I've applied to my file. I've corrected my work, but I have not found my mistake...
I confuse sir...Help me... :'(

Fu-Kwun Hwang

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Re: EM circular polarized wave
« Reply #6 on: May 24, 2010, 10:24:39 am »
Please upload your ejs source (xml) file and explain what you have done.

j.h.goh

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Re: EM circular polarized wave
« Reply #7 on: October 25, 2010, 05:10:52 pm »
Hi Sir,

I just want know, if I transmit a EM wave in a circular cavity, is it I will create a circular polarization?

Fu-Kwun Hwang

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Re: EM circular polarized wave
« Reply #8 on: October 25, 2010, 06:36:16 pm »
The answer is No (normally).
Circular wave is due to there is 90 degree phase difference between two polarization waves.

You can create such phase difference if the wave speed is different when electric field is in different direction (different polarization).
i.e. two different refraction index values for different polarization.

You need to understand the meaning of polarization of wave to understand it.

j.h.goh

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Re: EM circular polarized wave
« Reply #9 on: October 25, 2010, 07:30:37 pm »
Thank you for your reply Sir,

I have another idea, if I using the Vector Network Analyzer (VNA) to sweep the frequencies range in circular cavity, is it will generate a circular polarization?

Because different frequencies will have different wavelength, is this right?

or I could used a loop antenna to propagate the frequencies (from VNA) in the circular cavity, this will make different?



thank for all your helpful answer.

Fu-Kwun Hwang

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Re: EM circular polarized wave
« Reply #10 on: October 25, 2010, 10:10:48 pm »
Circular polarized wave means two wave with the same frequency but different polarization (Electric field are perpendicular to each other),
and the phase between those two electric field is 90 degree. It is circular polzrized if the amplitude of those two electric field are the same, otherwise, it is ellipse polarized.
 

lookang

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Re: EM circular polarized wave
« Reply #11 on: February 27, 2020, 09:09:05 am »
Dear Prof Hwang,
i would like to add https://en.wikipedia.org/wiki/Circular_polarization
the helical line that joins up all the ends of the E vectors.
the AnalyticCurve3D (EJSS_DRAWING3D.AnalyticCurve) in RED.

could you add it on your source EJS and i will try to study it or alternatively you can also add on my source EJSS?
https://iwant2study.org/ospsg/index.php/618

Thanks!

my initial attempt is
 functionX = Ex[0].toFixed(3)+"*cos("+_view._format(omega,"0.000")+"*c)"
 functionY = "c"
 functionZ = Ez[0].toFixed(3)+"*cos("+_view._format(omega,"0.000")+"*c)"

but the correct formula looks very complex, thought i better check with you, rather than i try to brute force the equations out by myself.
Thanks!
« Last Edit: February 27, 2020, 09:13:12 am by lookang »