At 9:35 AM -0500 4/4/03, Jerry Connelly wrote:
>...has anyone tried using two balloons with a dipole strung between them?
No; but, if I did, I would minimize the weight of the feedline by
Zepp and/or Windom feeding. Zepp feed uses a two-parallel-wire
feedline, one-quarter-wave long, with one wire connected to the end
of a half-wavelength antenna wire and the other feed wire floating.
Windom feed uses a single-wire feedline connected to a
half-wavelength antenna wire off-center. At the transmitter end, the
single wire is driven against "ground."
Zepp-Windom feed uses a two-parallel-wire feedline, one-quarter-wave
long, with one wire connected to the half-wavelength antenna wire at
the 60% point, and the other feed wire floating. The input impedance
at the transmitter end of the two-parallel-wire feedline is 50 ohms,
and no additional balun is required. A very excellent antenna, which
I have used in the field, for QRP DX.
I'd make the two-parallel-wire feedline of thin Litz wire, with
sections of plastic drinking straws for spacers.
73 de Chuck, W1HIS
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