On Wed, 22 Jun 2005 20:56:44 -0400, "Robert Morein"
wrote:


The twinlead
from a folded dipole is part of the antenna system itself. Therefore, it
picks up more signal, which can cancel with that received by the nominal
antenna.

********! (7)
It is a balanced transmission line which is matched to the balanced
300ohm folded dipole. The fields associated with the twin conductors
of the feeder cancel in the far field. It cannot radiate/recieve
itself if it is properly balanced.

Back in the 60's, people would prewire their houses with twinlead
for a rooftop TV antenna, and the ghosting (visual multipath) was vicious.
Replacing it with coax eliminated the distribution system as a secondary
antenna.


"twinlead" has lower losses than coax, (for similar size/cost)
however the disadvantage is that the fields extend outside the bounds
of the cable, whereas with coax it is within. To get the best out of
balanced feed it should be spaced away from other materials. Coax can
be attached to walls, taped to metal poles, etc. It also needs a
decent balun to connect to a dipole.