If the twin-lead portion is lambda/4 x Velocity factor,
and you add sufficient wire to the end to extend the
total length to lambda/4 you will find it gives a
reasonably good match to 52ohm coax. I built one
once. It went halfway up my tower and was then folded off at an angle and
the top end tied to to a fence.
It was cut for 75M and was a remarkable performer.

A chum of mine who DXes the low bands put one
up and really liked it. The antenna is described in Bill
Orr's book "All About Vertical Antennas".

Irv VE6BP

"Ian Jackson" wrote in message
...
In message , W5DXP
writes
On Thursday, June 6, 2013 8:34:04 AM UTC-5, Geoffrey S. Mendelson wrote:
What do I have?

http://en.wikipedia.org/wiki/Folded_unipole_antenna
--
73, Cecil, w5dxp.com

I think what Geoff is describing is not the usual folded unipole (twin
feeder shorted at the top, and at the bottom, one side fed from the TX,
and the other side grounded and/or connected to radials), but rather twin
feeder where the top end is shorted, and at the bottom, one side is fed
from the TX, and the other side is open circuit.
--
Ian