Assuming you are talking about a full wave loop antenna:

Maybe read the info at URL:
http://www.bloomington.in.us/~wh2t/loop.html
AND
http://hamgate.sunyerie.edu/~buffaloam/loop_antenna.htm

Depending on height above ground, a loop's impedance is nominally 100 ohms
So you can take it from there.

Baluns are described in detail at an ARRL site:
http://www.arrl.org/tis/info/pdf/8004019.pdf

More to them than just impedance matching -- such as common mode stuff

--
The generation of random numbers is too important to be left to chance.



"bpnjensen" wrote in message
om...
Hi, folks (and maybe CW) - on his helpful hints pages, CW (kc7nod)
recommends the possible use of a balun (which I take to mean a
transformer?) at the coax-antenna junction of a loop antenna...

http://www.kc7nod.20m.com/loop.htm

In this instance, can anyone advise what the ratio on this would be?
4:1? Another value? I'd like to try out this antenna design, and the
balun idea too.

Thanks,
Bruce Jensen