I must note here that the biggest disadvantage of trying to use an indoor antenna for DTV reception at UHF is not signal strength, rather multipath (radio waves echoing). In the day of analog television, multipath was visible, often on the form of "ghosting" (things in the image being "repeated", usually to the right of the actual image), or, in worse cases, the picture would fade out and/or start rolling. In digital TV, if if there is too much multipath (and it does not take much multipath at all), the decoder won't be able to make sense of the numbers and all you'll see is the "no signal" graphic on your TV screen.
With indoor antenna reception, one needs to forget the concept of "range". There are people who live 50 miles from their TV stations who get perfect reception with a small antenna on top of their set in the living room (e.g., by a window, overlooking a large yard, facing the stations), while there are people a mile or less from the local transmitters who haven't a prayer of getting OTA DTV. Using a (pre)ampifier will do NOTHING to alleviate multipath, just as you can't understand anything in a recording of dogs barking, be it from a small transistor radio or a 1,000 watt PA system.
While we're on the subject of "range" - Antenna manufacturers really shouldn't be allowed to quote ranges in their advertising, and consumers should learn to ignore any and all mentions of "range". These figures are chosen arbitrarily, almost always corresponding to the cost of the antenna, as their is no scientific way to quantify the "range" of an antenna. I've seen UHF DTV from 300 miles using an unfurled jumbo paper clip, and analog TV from 1200 miles using just the whip antenna built into one of those 5" B&W sets that were ubiquitous in the 1990s, but anyone who says that one can get useful TV reception (i.e., 98% of the time, not 2% of the time) from 150 miles with their TV antenna is flat out lying.
Once you get to the point of a modest VHF LPY/UHF corner reflector with about a 70" boom (Antennacraft 5884 may be an example - Winegard had better examples, but discontinued them all), any further improvement (longer boom and more elements) becomes incremental, with returns diminishing the further you go. A truly large antenna (e.g. Winegard HD8200) can solve some problems that may be beyond a smaller antenna, but the greater directionality can also cause problems. A station 30° off the beam may come in fine with a smaller antenna, while an 8200 could reject the direct signal from the same station and receive a signal ruined by multipath instead. A rotator, or course, answers that problem, but they can be inconvenient and many newer rotators have reliability issues.
As for your problem 45 miles outside of ATL - all I can say is try to get you indoor antenna somewhere where it is some distance from electronic gadgets, metallic surfaces, and the paths of people, and try different such locations inside the apartment. Oddly, reception may, in some instances, be better in a room facing away from the TV stations than in a room facing them.
One last question: Did you ask the apartment management if they have a master antenna? It used to be almost standard in apartment buildings, and while some apartments removed the master antenna and connected the cables to CATV, some still do have a master antenna (perhaps you should consider moving to an apartment that has one?)
