It sounds like the antenna was mounted in an area of masonry that was not reinforced. Masonry is pretty sensitive to eccentricity and moments caused by eccentricly mounted items. This could be a problem, both from a wall integrity problem and as a safety issue. If a chunk of wall falls out (which it could based on your description) then whatever is below could be adversely affected. If this occurs on an outside wall where it could fall to the ground, you must warn immediately. If the antenna and wall section can fall onto an existing roof, consideration should be given to how well the roof could handle such an impact. If it is suspected that the roof would fail under the impact, again, something should be done immediately.
The antenna should have been mounted only in an area of structure competence. Investigation must be done in order to establish this competence. In the event the wall is not competent, then alternate design must be done for the antenna, and also remediation of the wall to restore competence should be done.
This can likely be remediated as it sits. The antenna should be removed and then the tie beam can be jacked up slightly and the masonry pulled or pushed back into position. Some positive reinforcement of the masonry should then be done to establish a tie to the tie beam. A steel angle frame could be put on the inside of the wall that would span between the tie beam and the floor, to which the antenna could then be mounted on the outside of the wall with through-bolts, or plates/angles could be mounted on the outside with through-bolts, then the antenna mounted to the plates/angles.
Since the lateral stability of the wall has now been compromised, I would establish some vertical reinforcement in the wall and fill the cells on a reasonable spacing pattern considering the expected lateral loads (typically wind) for the area and height of the building.
Have fun!
I'm not sure what area this is in, so I don't know your code requirements. Perhaps it was designed and built correctly, just not to handle additional equipment mounted on the outside.
