The easiest antenna by far to make is the simple loop antenna. If you have one channel that's difficult to receive, you can tune it specifically for that channel.
Get a 75ohm coax to 300ohm twinlead adapter, then a piece of solid copper wire such as from Romex.
Look up the
frequency of the channel you are trying to optimize for here. Then from:
Wavelength (Lambda) = Wave Velocity (v) / Frequency (f)
or your favorite online frequency to wavelength calculator, determine how
long to make the wire. Add a couple inches so you can add loops on the ends.
Bend the wire into a circle by hand, and bend little loops in both ends of the wire with needlenose pliers so it can be screwed into the twinlead terminals.
Done
Or you can...