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vrf circularly polarized antenna

Question asked by VRFuser on Jan 24, 2008
Sook Foong Law <> wrote:
> I am now designing a circularly polarized antenna by couple a
> rectangular microstrip antenna with a 3dB branch-line coupler. As i am
> designing in MOMENTUM, i look at the 2D plot to check whether it is
> circularly polarized or not.

>  However, I am not so sure whether the result is ok or not.
>   I wish to ask whether anyone know how to see the result?
>  Is it I need to see the axial ratio at 0 theta?

I know that this is off-topic for VRF, but please bear with me as it may well be of interest for the many VRF folks who are high frequency designers.

Here's answer from EESOF Support folks ( )

"To check how well the antenna is circular polarized, after you define the port feed and make the 2D cut plane for antenna far field radiation pattern and the 2D data display for radiation pattern is open, you can check the plot for Axial Ratio for Circular Polarization.

The axial ratio describes how well the antenna is circular polarized. If its amplitude equals one, the fields are perfectly circularly polarized. It becomes infinite when the fields are linearly polarized.

You can also check linear polarization axial ratio plot for linear polarization.
This value illustrates how well the antenna is linearly polarized. It equals to one when perfect linear polarization is observed and becomes infinite for a perfect circular polarized antenna."


Stan Bischof  Agilent Technologies  707-577-3994

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