Basic cell phone signal booster

I have shifted to work in an office within a basement... obvious consequence: low cell phone signal, battery drainage, missed calls and calls that get cut.

I wanted to try out a cell-phone signal passive repeater, but for that you need 2 antennas, and so far, I've been able to get only one. But it is already helping me!

It is a small antenna from a surveillance system with wireless cameras (picture below).

With this small antenna, I just have to open the receiving plate, place my cell-phone right in front of it, and in a matter of a few seconds, the signal goes from practically null to about 80%. 

This helps only for avoiding battery drainage and missed calls, because once you move the cell-phone far from the antenna (i.e. when you speak on the phone during a call) the signal again reduces a lot... but is quite some help for something that took no effort at all.

I hope I manage to get another antenna so as to try out the passive signal repeater soon.