Antenna Q

So, I was thinking of something else, and thought, once again, about
building a little Yagi for local UHF. A little googling turned up:

http://members.shaw.ca/weskyscan/3ElementYagi.htm

Which has the formula right there, which is cool, but I'm wondering,
to what degree is this scalable, and what kind of parasitics do I
have to account for? I'm looking at US UHF broadcast - the highest
channel I usually look at is 58, but there's one at 56 which seems
to come in pretty OK with a little random wire, but when I move it
around for the best reception, as soon as I move my hand, it
detunes it.

Well, I live at a weld shop (actually, they do both - welding
and machining) so can get practically unlimited quantities of
aluminum or steel or alloy rods, from .040" up to about 3/16"
diameter. So I could just cut a few pieces and tape them to
a popsicle stick, and I'd have an antenna - but I still have
to match it to the input of my battery TV, which expects a
whip.

Any suggestions on that, as to what kind of coil would match
it well, and what I do with the other end of it? I do have
access to chassis ground through the wall wart connector.
- I just looked - it has a jack labeled "EXT.ANT." - looks
like an ordinary 1/8" phone jack - whould I take a WAG that
that one might be low impedance? (prob. 75) And how do you
make a balun for 722 MHz?

Thanks,
Rich