Just for add.
important to know :
the Passive Gain of Antenna is bidirectional, but Tx Active gain (Tranceiver) is unidirectionnal. So the better choice , is always choose a low power tx for a middle passive gain antenna.
exemple for a 7.5 dBi gain antenna (like ANT-28) use a tx power max at 10dB for client coverage to be sure to have a good biderectionnal communication.
And always do a survey to validate ;-)