I've gotten a few emails asking how a 1/4WL wire stub can be
used as a balun on a single band like 2m. Just connect the
wire to the element driven by the coax center conductor and
connect the other end to the braid 1/4WL down the coax. In
fixed font:

|
|
| Dipole
|
|
+====================================coax braid

+------------------------------------coax center conductor
|
| ===================+==============coax braid
| spacing |
+---------------------+
| 1/4WL stub
|

The current at the feedpoint sees a very high impedance looking
back down the *outside* braid of the feedline because it is looking
into a shorted 1/4WL stub. Often, a piece of similar coax is used
for the 1/4WL stub.
--
73, Cecil http://www.qsl.net/w5dxp