Roy Lewallen wrote:

I also believe that while you might draw some possible parallels, you
can't directly apply the characteristics of an antenna in proximity to
an infinite reflecting plane (as in Kraus) to those of an antenna in
proximity to a tower.


Roy is gallantly trying to be non-commercial about this, so someone else
had better say it:

Download the free demo version of any NEC-based antenna modeling
program, and model the effects of the actual tower geometry. It's the
only way to see what's really happening.

You'll get a good first approximation by modeling the tower as its three
very long vertical legs. Since you're only interested in the effects of
the tower on the J-pole's omnidirectional pattern, you can use any kind
of vertical omni to model the antenna itself - a center-fed dipole for
simplicity.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek