[Antennas] Log Periodic-Grounded antenna systems

2002年5月23日 14:47:56 -0700 (PDT)

George, I agree totally your comments about Ground, and
the history of why it is used, etc. I think the whole
idea comes under the subject of 'Ham Radio Lore'.
 I've begun thinking about this subject and have
concurred that grounding the feedline ANYWHERE is not a
good idea.
 I am going to be giving a presentation at the local HR
club and am going to use an example of operating field
day on a 66' metal forest service tower with a 66'
dipole on 40 meters.

 Imagine the dipole is strung such that it intersects
the tower at the 66' level. Now ground the rig to the
tower. Where do you attach the negative side of the
dipole??? To the tower of course. Does this make sense
??? Isn't the tower now part of the antenna system? 
SInce the tower is 1/2 wavelength long, it is a dead
short to ground on 40m. On 80 or 20 meters, the tower
is now insulated or isolated from ground.
 Isn't any grounded feedline part of any antenna system
?
 Pat W0OPW

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