I tested a patch antenna in a Satimo anechoic chamber and then tested it again using the EMSCAN. I found the readings very close. The gain was almost the same while there was 10% difference in the measured efficiency. I am still new to EMSCAN and I am working on it. I will test more antennas of other types and compare the results.
Very interesting indeed. If you have more results, please update. I'd be very grateful if you can send your comparison anyhow. Did you check the TRP results, or did you use coax launching which is more prone to error?