I get great reception with a homemade antenna. If you have a ruler, a drill, and something to cut wire, you can make one pretty easily. Look up the "Gray Hoverman" antenna online and look for the ones that are just screwed to a wooden board, not the crazy ones made of PVC pipe with reflectors. Mine has the wires simply screwed to the board with washers to hold them down. Costs about $20 for parts that you can get online.

Be careful about putting antennas outdoors, since they can attract lightning and have to be grounded properly. I put mine in my attic (2-story house) and hooked it to coaxial cable already in place from when the house had cable TV. It picks up ABC, NBC, Fox, CW, My48, and Ion crystal-clear. PBS is a little wonky sometimes.

If you do put it outdoors, as an alternative to drilling through walls or floors, you can run cable under a window sash with flat coaxial connectors lke these.