I actually went on youtube and typed in "how to build cheap digital antenna" and we did-It was less than 10.00and cheap stuff from lowes.I get about 12 or13 channels.We got to where we cant afford cable anymore
You need a signal analyzer on a converter box to tell you the signal strength improvements.
I made this one for my mothers place 2 years ago to test it out for the fun of it ~35 miles from downtown Chicago.
IT definitely helped the signal pickup, but the manufactured models were 2x as receptive that were the same size.
This is the unit I tested it with side by side using a signal analyzer to see which caught the signals better.
IT blew my home made one out the water.