this is a screenshot of my "current tx power" tab on my hAP Lite.
so, this shows that the AP can transmit signals at 19 dbm. but only for lower data rates.
now, this is the question. what prevents the radio to use its maximum power to transmit higher data rates? why it can't transmit electromagnetic waves at full power, if they are modulated differently or with other MCSs?
for example, for data rate of 54mbps, it only uses 15 dbm of power. as you know, 15dbm is about 2.5 times weaker that 19dbm!