(i use approximately 1 mm copper wire thats used in most of the house wiring here now. A biquad is very simple, as long as you get the measurements and use the right kind of wire. I still have one of them and I went back recently to see how well it resonated since now I have a vector network analyzer. In the distant past (back when I speht a lot of time in nearby cafes and needed to use my home Internet connection, as I did not want to pay for theirs) I made several biquad antennas based on designs I found on the web. I would ditch the Yagi and make a biquad antenna instead.
