polarization of a patch antenna

Hi. I want to plot polarization of a patch antenna. I'm using HFSS, but that shouldn't make a difference because my questions regard the topic of polarization and not the simulator.

My patch radiates in the negative z-direction. It should be circularly polarized. I want to know how to measure this.

From the pic: phi sweeps around the x-y plane & theta sweeps around the z-axis.

I think I want to plot the polarization ratio when theta is 180 degrees since that is the direction of maximum gain. What should I choose for phi? I want to compare the electric field of Ex to Ey. I think that's correct.

Do I need to plot gain in the x-dir and gain in the y-dir?

Please let me know. thanks.

A really complete discussion of polarization can be found in this reference:

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

There are a variety of methods to measure circularly polarized signals. You can measure orthogonal linear components and the relative phase if you have sufficiently sensitive receivers. You can also consider using circular sources and gain standards.

Spend some time with the book. This is also a subject that regularly comes up here so use the secret (search) feature.

Azulykit. i've used the search box before. that's how i remember that you posted that same response to another post. in that post that you replied to the problem didn't get solved. most polarization responses are not fully solved. that's why i posted this question. maybe someone knows the answer.

as i said before. i want to compare the Ex to Ey polarization . i know there is a choice called ludwig, but i'm not sure if that's what i want to use. I know I want to look at the polarization in the theta = 180 degrees direction, but i don't know where to go from here. is it correct to just plot theta = 180 degrees and plot gainX and gainY?

thanks.

Hi,

usually polarization definitions have a singularity at th = 180° even with 3-rd ludwig definition...
Can you re-orient the antenna ? I mean consider a new coordinate system with antenna positive Z-Axis in your direction of interest...
In this case at the new boresight (the old th=180°) you wull have a well defined X and Y pol...

Bye.