circular patch antenna measurements

[dch316]

hi all,
Can I measure, or at least characterize in some way (axial ratio e.g.), a Circularly polarized antenna in an anechoic chamber where the known antenna has linear polarizacion?
thanks

 

[vfone]

I don’t think is possible. Polarization mismatch between linearly and circularly polarized waves is not constant and depends by the circularly polarized wave’s axial ratio. For different axial ratios the mismatch could be somewhere between 0 and 10dB.

 

[caocao]

hi all,
Can I measure, or at least characterize in some way (axial ratio e.g.), a Circularly polarized antenna in an anechoic chamber where the known antenna has linear polarizacion?
thanks

Hi dch316,
About the measurement of circulary polarised antennas in anechoic chamber such as Compact Range, if u only measure the AR on some angle, you can choose the polarization of the linear source (H or V) and tune the antenna to the angle, circumgyrate it along its axial! If the pattern is almost circular, we can conclude the antenna is CP antenna because its two polarization component are equal, but we don't konw the CP direction.
Of course, a tilt linear polarization or high cross-polarzied antenna have the same character too! You have to judge based ur knowledge.
Regards!
caocao

 

[dch316]

Thank you guys, I think I will be able to measure what caocao said while waiting for the true CP antenna.
regards