[TenTec] Transmission Line Names

[Ken Brown]

There has been a lot of discussion lately about various types of two 
wire parallel transmission line. I am a bit confused about what each 
person is actually talking about when using various terms such as ladder 
line, open wire feeder, window line, etcetera.

I thought that ladder line was called that, because it is two parallel 
wires, with their spacing maintained by insulating rods of ceramic, 
polyethylene, paraffin soaked doweling or other plastic material. It 
looks like a miniature rope ladder. How does open wire feeder differ 
from ladder line? Or is it another name for the same thing?

I thought that window line was essentially jumbo sized TV twinlead, with 
rectangular holes punched in the flat polyethylene (or other plastic) 
separating dielectric material the maintains the spacing between the two 
wires. Is that the correct? Most of what I have seen, that I thought was 
called window line, is dark brown or black.

By TV twinlead, I am referring to the 300 ohm flat "ribbon cable" that 
was commonly used for TV antennas, before coax became the norm. Often 
AM/FM Stereo receivers or tuners would be supplied with a folded dipole 
made out of this 300 ohm ribbon cable. It is usually translucent white 
or dark brown or black.

I have also seen variations of  TV twinlead, which instead of having a 
flat section of plastic between the two wires, have a round or 
elliptical cross section piece of foam between the wires. What is that 
called?

And there is another kind of twinlead, which looks a bit like large zip 
cord, or telephone service drop wire. What is that called?

In order to have an intelligent discussion, we need to understand what 
we mean by the words we use.

DE N6KB