"joe" wrote in message ...
Many antennas are built using tubing for light weight. So, if there is a
current flowing in the middle, it is good that the ends of the tubes are
crimped, or plugged. I wouldn't want the flowing electrons spilling out
onto my lawn.

thats why they put those plastic plugs on elements, to keep the magical
mystery dielectric particles from falling off instead of going back up the
middle... if you ever lose the plastic caps you will notice the antenna
starts leaking and the particles pileup in your yard making a real mess.