dumb sounding ladderline question
 

Dumb sounding question----but-----with a ladderline fed dipole, is the
feedline supposed to radiate and be part of the antenna, under some
conditions?

Dumb sounding question----but-----with a ladderline fed dipole, is the
feedline supposed to radiate and be part of the antenna, under some
conditions?


NOT a dumb question. I was always under the impression that radiation
from the two parallel wires in ladderline was supposed to cancel itself
out... ergo no radiation. That's why they call it a balanced feedling.


Ed K7AAT

The G5RV has been said to radiate from the feedline.

"RB" wrote in message
...
Dumb sounding question----but-----with a ladderline fed dipole, is the
feedline supposed to radiate and be part of the antenna, under some
conditions?

On Wed, 05 Oct 2005 19:56:48 GMT, Ed
wrote:


Dumb sounding question----but-----with a ladderline fed dipole, is the
feedline supposed to radiate and be part of the antenna, under some
conditions?


NOT a dumb question. I was always under the impression that radiation
from the two parallel wires in ladderline was supposed to cancel itself
out... ergo no radiation. That's why they call it a balanced feedling.


Ed, your unstated assumptions is critical to the correctness of your
statement.

At sufficient distance from the parallel line, the fields from each
conductor are canceling providing the currents in each conductor are
exactly equal in magnitude and exactly opposite in phase. Under those
conditions, the parallel line is also balanced feed line.

Achieving those conditions (or a sufficient approximation) doesn't
happen automatically in the real world. There are all manner of things
in practical applications that would cause unbalance in the currents
in the conductors.

If the currents are not balanced, the fields will not cancel, and
there will be radiation to some extent, so the feed line does indeed
become part of the radiating system to some extent. Conversely, feed
line capture would contribute to some extent to received energy.

Owen
--

Owen Duffy wrote:
On Wed, 05 Oct 2005 19:56:48 GMT, Ed
wrote:


Dumb sounding question----but-----with a ladderline fed dipole, is the
feedline supposed to radiate and be part of the antenna, under some
conditions?


NOT a dumb question. I was always under the impression that radiation

from the two parallel wires in ladderline was supposed to cancel itself

out... ergo no radiation. That's why they call it a balanced feedling.



Ed, your unstated assumptions is critical to the correctness of your
statement.

At sufficient distance from the parallel line, the fields from each
conductor are canceling providing the currents in each conductor are
exactly equal in magnitude and exactly opposite in phase. Under those
conditions, the parallel line is also balanced feed line.

Achieving those conditions (or a sufficient approximation) doesn't
happen automatically in the real world. There are all manner of things
in practical applications that would cause unbalance in the currents
in the conductors.

If the currents are not balanced, the fields will not cancel, and
there will be radiation to some extent, so the feed line does indeed
become part of the radiating system to some extent. Conversely, feed
line capture would contribute to some extent to received energy.

Owen
--

Would twisting the ladder line help?

--
William Warren

(Filter noise from my address for direct replies)

On Wed, 05 Oct 2005 17:33:45 -0400, William Warren
wrote:

Would twisting the ladder line help?

No


Danny, K6MHE

email: k6mheatarrldotnet
http://users.adelphia.net/~k6mhe/

On Wed, 5 Oct 2005 16:00:47 -0400, "Fred W4JLE"
wrote:

The G5RV has been said to radiate from the feedline.

Only if it is unbalanced (such as not installed sysmetrically).

Danny, K6MHE

email: k6mheatarrldotnet
http://users.adelphia.net/~k6mhe/

The G5RV has been said to radiate from the feedline.

Only if it is unbalanced (such as not installed sysmetrically).

Danny, K6MHE

If each side of the dipole is bent asymmetrically, then very little
imbalance in feeder currents is evident. Off center feeding a dipole does
unbalance feedline current. A double extended zepp is a good example of an
unbalanced feedline with significantly different currents in each leg. It
would be interesting to see just how much power is actually radiated from
the feedline of such an antenna.

Frank

Frank wrote:
A double extended zepp is a good example of an
unbalanced feedline with significantly different currents in each leg.

Not true. The "double" means it is a balanced dipole.
An EDZ is simply a 1.25 WL center fed dipole. The
currents are supposed to be balanced.
--
73, Cecil http://www.qsl.net/w5dxp

"Cecil Moore" wrote in message
m...
Frank wrote:
A double extended zepp is a good example of an unbalanced feedline with
significantly different currents in each leg.

Not true. The "double" means it is a balanced dipole.
An EDZ is simply a 1.25 WL center fed dipole. The
currents are supposed to be balanced.
--
73, Cecil http://www.qsl.net/w5dxp

Ok, so I used the wrong name. What I meant was an antenna fed at the end
with open wire line, with one side of the feedline unconnected. Is it
called a zepp?

Frank