Kralt wrote

Do I need 2 antennas to extend wifi signal out doors to barn 150 feet away

Not necessarily. If the devices in the barn fall into the 65º antenna beam width angle of the CPE210 and if the devices have good antennas themself to send a strong signal back to the CPE, it can work over 150ft.

But if you experience weak WiFi signals from the client devices, you should consider to use two CPEs and probably an additional AP with omnidirectional antennas (360º beam width) wired to the CPE in the barn:

Thus, it depends on the clients you want to connect to the CPE.

Also check out EAP225-Outdoor. In my opinion this device does fit better over only 150ft and if client signals are too weak, a second EAP225-Outdoor in the barn linked wirelessly to the first EAP would replace a CPE/AP combo:

Note that for connecting two EAP225-Outdoor wirelessly you would need an OC200 controller (just in case you consider this method in favour of CPEs):