[TenTec] openwire feed OT

[James Duffer]

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.