On 14 sep, 01:10, Cecil Moore wrote:
On Sep 13, 5:19 pm, Owen Duffy wrote:

The NEC model I posted
shows that a 1k isolator (common mode choke) is not effective for that
purpose.

Here's a model of a Carolina Windom on 20m with a 2k choke (isolator)
20 feet down the coax from the antenna feedpoint at a height of 50
feet. The maximum current on the coax braid above the isolator is 0.72
amps. The maximum current on the coax braid below the isolator is 0.14
amps. The radiation pattern is close to the advertised one for 20m.

http://www.w5dxp.com/carwin20.JPG
--
73, Cecil, w5dxp.com

Hello boys (greteengs Wimpi, how are you?

For monoband applications we can get more Z from a coaxial choke
making the winding for autorresonance. K1TTT have a good data table.

Time ago I want test differents antenna to lift with a kite and I
found =
http://www.io.com/~n5fc/rfd.htm, the idea seems to me interesting
enough to make some test that are descibed here =

http://www.solred.com.ar/lu6etj/tecn...evisada-en.htm

from here I think of another use of de "coaxial trap" to get more Z
from coaxial winding specially in monoband antennas, I named de
critter "The Trap balun" =

http://www.solred.com.ar/lu6etj/tecn...a_balun-en.htm

4NEC2 simulations and real field test show me both approachs works
fine :)

Miguel Ghezzi LU6ETJ