return loss and co-polarization

When calculating or measuring the return loss or S11 for an antenna, is it only considering the copolarization wave reflections only or is it considering both the copolarization and crosspolarization waves reflections?

Any antenna is tested against a standard antenna in co-polarized response. Orthopolar response is considered not desired.
If testing for S11 as return loss, orthopolar response may be considered as unwanted loss, therefore IMPROVING S11 as the orthopolar radiation does not return back to the source.

will the orthopolar response (X-pol) be included in the S11 measurement? Or is the X-pol measurement independent from the S11 measurement? In other words, does S11 represent co-pol coupling response which is different from x-pol coupling response?

Thanks.

As I wrote, polarization properties of an antenna can only be evaluated against a "standard" opposite antenna. S11 only represents the return loss, so in fact if some radiated power is lost as orthopolar radiation, such part will not be returned as reflected back to the source, therefore S11 will improve b such part.
S11 does not have any link to any polarization- it only represents the power ratio from and to the source caused by the tested antenna.