I've checked what kyjackchan said above and here are my observations. Please give your comments also.
Cross-polarization according to HFSS:
The maximum gain (max of the radiation pattern in dB) is located at the same *ANGLE (theta or phi)* in both COPOL and CROSSPOL.
This is WRONG and cannot be verified EXPERIMENTALLY because:
....... In test-chamber, when the 2 antennas are cross-pol, the gain has to be MINIMUM. Example when the 2 dipoles, one receives, one transmits, are parallel (4 meters away), the gain is maximum, and when the 2 dipoles are 90 degrees, the gain has to be MINIMUM.
....... Maybe I'm wrong because in HFSS, I draw only *ONE* antenna, not one transmits, one receive.
What are your comments ?