circular polarized microstrip

hi all,
here i need some help to identified the circularly polarized for microstrip antenna.
how can i show that my design is a circularly polarized? i've search in internet n book but still confius bout circularly polarized. my antenna design is circular patch microstrip antenna at 2.4GHz. i've done my design simulation by using CST microwave studio. can any body help me up to show that my design is a circularly polarized from the simulation result?
thanks

Hi

You can plot the Left Hand Circular Polar (LHCP) gain and Right Hand Circular Polar (RHCP) gain in CST. If one of them is over 10-15 dB higher than the other you have that polarization. If they are the same, then it is linear polarized.

Regards

hi,
thanks tyassin for your info. here i've attach the 3d of RHCP of my design. can u help me to ensure that this is a circularly polarized. sorry that i didn't attach the LHCP coz my design is for RHCP. can u help me?

Hi

I cannot tell from this plot. If you can plot the LHCP and RHCP in the same rectangular plot, then it is much easier.

Axial Ratio will give the purity of Circular Polarization.
So with the help of axial ratio plot we can get an idea whether it is circularly polarised or not?
Ideal axial ratio plot will be within 1 dB but in pratical case up to 3 dB is accepted.

regards,
balaguru.

Couldnt it be 0 dB for an ideal case and do you think in practical cases upto 3 dB of axial ratio is accepted for CP.

Sorry guys for ideal case its 0 dB
and practical upto 3dB is accepted.

applies to every circular polarized antenna?

To check circular polarization in CST, i have to put 2 modes in waveguide port..after the simulation i combine results and i only see if is circular polarized in the farfield combined result? or simulating with only 1 mode, i can see if is circular polarized or not?

I′m bit confused, since the manual dont have much information about polarizations

thanks.

Look up this book:

Stutzman, Polarization in Electromagnetic Systems, Artech House, Inc., 1993.


It will explain what you need to understand about the various polarizations.

From the reviews that i read, it looks like the perfect book for my needs...but unfortunately sending from US+ship+custom taxes.....

Do you recommend another book about polarizations?

I guess you will have to decide what you can afford. That is the hard part in engineering.



Good.
Fast.
Cheap.

Pick any two.

applies to every circular polarized antenna?

To check circular polarization in CST, i have to put 2 modes in waveguide port..after the simulation i combine results and i only see if is circular polarized in the farfield combined result? or simulating with only 1 mode, i can see if is circular polarized or not?

I′m bit confused, since the manual dont have much information about polarizations

thanks.