calibrated circular-pol antenna?

Hi, all. I am going to measure a circular-pol antenna, and have a question about the calibration. Where can I find some calibrated circular-pol standard antennas for calibration?

I found some dual-pol antenna, but it requires extra 90 degree coupler to generate circular-polarization. So I am thinking if the mismatching for coupler and antenna increases the uncertainty of measurements?

Or can I use standard linear-pol antenna, and make two-sets of measurements including the theta and phi fields magnitude and phase to calibrate the circular-pol antenna? If so, are there any references about that?

Thanks.

Hi

you can use hfss to build one.
or buy from

http://www.ticra.com/script/site/pag...d=10&cat_id=26
http://www.ticra.com/script/site/pag...d=11&cat_id=27
http://www.ticra.com/script/site/pag...d=12&cat_id=28

pl