[ngarrang]

If I were interested in building a Yagi and wanted it to best serve the new UHF range, what is the target size for the driven element to insure that I capture the frequences above and below it?


I am trying to read up on the yagi design, have found the yagi desing utilities, but this particular answer is eluding me.

 

[Colm]

You generally want the driven element to be resonant at the center frequency of the band. Its electrical length should be 1/2 the wavelength of that center frequency. Note that the physical length of the element will less than 1/2 wavelength because the cross section affects the electrical length. Just use the length given by a good design program. If you build the antenna exactly to specifications, it should work well. Note that professional antenna designers don't stop here. They take the prototype antenna to an antenna field, measure its performance, and tweak the design to optimize the performance. There is a lot of interaction going on in a Yagi. Changing element lengths and spacing will change the usable bandwidth and directivity.