Plus, I wonder if there are certain buildings where an antenna has to be installed professionally and not individually.

There are some buildings that are so dense you cant get an OTA signal. I know in the past, the gambling area at and along River Rd in Rosemont was one of them. There was a fund set up for those people at certain addresses to get free or subsidized cable due to not being able to receive the OTA signals.

Many Townhomes and Many Condos and some homes have an HOA that does not allow outside antennas at all.

Besides that, if an entity does not allow an outside antenna, the interested party will have to settle for an indoor setup.

Our resident PhilJSmith knows a lot more about this than I do, so I will defer to add on more info. :-)

Z