Re: [TenTec] openwire feed OT

["James Duffer" <dufferjames@hotmail.com>]

snip

> The impeadance of a dipole in free space is about 72
> ohms at the center feed point which is why you can
> feed it directly with coax.  Of course site conditions
> usually drop the dipoles impeadance quite a bit.

FWIW The impedance of free space (and a vacuumn) is approximately 377 Ohms.  
It too is referred to as Zo and is a physical quantity.  A horn antenna in 
radar or microwave serves as a match from the feedline (waveguide) and free 
space.
Jim de wd4air

> You can also feed the dipole with the higher
> impeadance open wire feeder and be ok because you are
> transfering power from a high impeadance source to a
> low impeadance load.  The key point here is that the
> antenna is the load, not another transmission line.