Connecto two buildings

Hi all,

our company wants to connect an office that is 150meters apart from main building.
The two buildings have direct line site but the office is in the opposite side of
the building, I'm not sure if I can have direct line site, but we can try.


| | | |
| | | |
| | | company |
|------- | <-- 150meters --> | building |
|office| | | |
| | | | |
------------------------------------------------------

Inside main building we use a Cisco aironet 350 AP to a small wireless network.
There is any possibility to use this equipment to connect to our office?
I think this model can't have external antennas.
I have seen some equipment from cisco and d-link, but some are very expensive.
Anyone can give me any suggestion for some solutions?

Thnaks