An antenna engineer gives you a test unit, telling you that an antenna's efficiency is -2dB when measured passively. You measure it actively and find that it is actually -3dB. What could account for the difference if there is nothing wrong with the calibration of the anechoic chamber? How could you prove it? If you measure active efficiency of an antenna as being -3dB, but you see that the TIS is 5dB worse than the conducted sensitivity for a given channel, what could be causing this if there is nothing wrong with your calibrations?
