I actually bought mine from one of the antenna places. I think they sent
a reprint of an article with it, but don't have a clue where that is any
more. Sory I can't be of more help. The length of the feed line varied
depending on what impedence it was and the volocity factor as I recall. I
had a couple commercial ones I bought, one used standard 300 ohm tv
looking wire and the other used ladder line about an inch or more
wide. The line lengths were different, but I'm not sure how this is all
calculacted.
73s
Butch WA0VJR