Current choke for an antenna

Hi all,

My question regards cancelling parasitic currents on an antenna pole.

I would like to mount a discone antenna on a metal-pole. The simulation shows a leakage current on the metal-pole which changes the radiation pattern of the discone antenna. I would like to design a sleeve choke for the pole.

1. Can anyone post comments or references about these current chokes?
2. Is there any suitable solution for wideband antennas as the discone?

Thanks alot,
P.