ohyeah :) very true  I use window line myself on y dipole. I didn't want to confuse him though
open line  twin lead or window line are much better for  multi band hf antennas as i have found out rom my experience :)  
On Aug 2, 2013, at 5:33 PM, "Alan R. Downing" <[log in to unmask]> wrote:

> There are other types of feed line too, including open or balanced line,
> often called twin lead, and hardline in various diameters, to name just a
> few.  Hardline is generally used for high power  stations, as well as for
> frequencies above 148 MHz.
> Also, if the distance from the transmitter to the antenna system is very
> long, 200 yards or more say, then hardline is a very good choice.  The
> longer the feedline is, the more loss you have.  Though the distance from my
> shack to my tower is < 100 feet, I chose to use 7/8 inch diameter hardline,
> transitioning to a large diameter type of coax for the vertical run up my
> electrically operated crank-up tower, called LMR600.  The result of using
> the combination of hardline and large diameter coax, is very, very low loss,
> in the range of quarter of 1 DB.  The total length of my feedline from the
> shack to the antenna is approximately 200 feet.
> 
> HTH
> 
> Best 73
> 
> 
> 
> Alan R. Downing
> Phoenix, AZ
> 
> 
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Michael Thurman
> Sent: Friday, August 02, 2013 1:55 PM
> To: [log in to unmask]
> Subject: Re: question
> 
> coax cable, called coaxial because it has a center conductor, and a =
> concentric shield conductor,  coax sharing the same axis. It is used =
> primarily as a feed line for rf to and from antennas, also between =
> components in an audio video system. there are  many different kinds  of =
> cable, from the thin stuff that comes with a cheap dvd player to  inch =
> or larger feed lines for commercial installations.  There are antennas =
> that use part of a coax cable, such as a coaxial dipole, where the =
> shield is pulled bak ove itself to form half of a dipole antenna, =
> leaving the center conductor and insulation, called the dielectric  as =
> half of the antenna., but most commonly it is used as feed line.  You =
> might be interested to know that although the shield is one conductor, =
> it functions as two conductors at rf  frequencies, which is why it works =
> well as a shielded feed line. the rf flows on the center conductor and =
> the inside of the shield, not the outside.. that is why you can make a =
> could out of coax, or use ferrite chokes to eliminate rf flowing down =
> the coax back to the shack.
> 73 kb7nla
> On Aug 2, 2013, at 4:32 PM, RJ Sandefur <[log in to unmask]> =
> wrote:
> 
>> What is coax? Is that what you make your antana from? RJ