K2AV writes:
Diversion of power to miscellaneous conductor paths is almost universally
lossy and never in directions and modes desired in our attempts at
directional arrays.
The common mode path on the outside of coax shields is lossy first because
it has a thick jacket which is never designed for low loss, second because
it often lays on the ground or is buried, a very lossy situation. Try your
20 meter dipole laying on the ground to check that out if you're not
convinced. And if that is not enough, coax is often taped to towers, making
it a transformer winding to the metal of the tower, whose reradiation is
certainly not going to be useful in a 4 square.
---------------------
Okay, let's put in those K9YC multiturn chokes at each feedpoint. This
provides a -resistive- load to the common mode path. In fact, these
chokes can get pretty warm. So, the way I see it, putting in common mode
chokes does nothing to reduce the system power loss that K2AV is so
concerned about.
73,
Steve, N2IC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|