Hey,
You should use a high 5 GHz channel to base your max distance on.
So I choose channel 140 or 5700 MHz.
You should transmit at no more than 14 dBm.
The antenna gain on 5 GHz is 6 dB, however the half power beamwitdth is 60 degrees so if you want to calculate for the entire 60 degrees you should subtract 3dB from the gain.
So you have 14 dBm transmit power and 3 dB gain on 5GHz for the entire 60 degrees.
This gives you an EIRP of 17 and you want to target no lower than -67 dBm receive power at the edge.
So you want your free space path loss to be no higher than 84 dB.
So 93 meters is your maximum for a very decent coverage.