When I am designing power amplifiers, I see that, especially for BJTs, I am quiet sensitive to my load variation. And in case of antennas, if there is a galvanic contact, the impedance changes quiet a bit. How is it handled in actual products, especially at mmWave?
So is the antenna impedance variation completely taken care of in such cases?
Also what about impact of process variation combined with antenna impedance variation?
Most credible Fab facilities should provide their tolerances. You can calculate/simulate the worst case scenarios and adjust your nominal design to compensate slightly for it. However, if YOU are the one doing the fab, no other way than to make a bunch of variations and measure them to gather those type of statistics.