The PBS tower is in Chapel Hill. Of course being in Garner, you probably barely need an antenna to pick the rest of the stations up, so you might be able to get by with a directional antenna aimed to PBS and it might pick the rest up too.
It's been so long since I was setting my antenna up that I can't remember their channel number since the digital switch was flipped and channels were reassigned. Try
AntennaWeb - Home and you should be able to get the heading and channel number there.