Ideally you would employ some sort of externally mounted antenna outside to bring in the best quality signal. Otherwise, it will be trial and error. Some of the new HDTVs just don't cut it.
I just bought a SanSung 24" TV. But the reception seems to break up quite often. I've tried 2 different antennas -- an RCA dipole and a RCA digital flat one (with and without amplification). The reception with my old Sharp analog TV with a Zenith digital to analog converter box was better -- only occational breakup of the signal; and I was using only a monopole antenna that had come with the Sharp TV. Any suggestions as to why the problem and how to fix it?