Most over-the-air broadcasts currently offer high definition (HD) picture quality with either 720p or 1080i resolution. This matches the resolution that most cable and live TV streaming services provide.  With that said, antenna-based broadcasts can actually look better than cable. Cable tends to compress video and audio quality more than antennas, so over-the-air TV will typically provide the clearest quality you can find in a broadcast. That is, as long as your reception is strong. Over the next few years, some over-the-air stations will begin to broadcast in 4K through the new ATSC 3.0 standard, aka NextGenTV. NextGenTV's 4K broadcasts are already available in markets like Pittsburgh and Phoenix, and will make their way to cities like Buffalo and Orlando throughout 2021.  If you want to keep your current antenna, you can, but you'll have to buy an ATSC 3.0 tuner or a 4K TV with a built-in ATSC 3.0 tuner to actually watch in 4K. You can find more information on when 4K broadcasts will become available here.