Topband: Vertical offset from center of radial field

[Charles Bibb]

Hi, all

I searched the literature and the topband mailing list archives for 
this info, but can't seem to find the answer.  The archives contained 
two queries almost identical to my question, but unfortunately no 
replies in answer.

My question is this:  How far offset from the center of the radial 
field can a vertical radiator be before encountering serious problems 
with ground losses and/or pattern skewing?

I'm planning on doing some antenna experiments this summer, and the 
feed-point of the "new" or experimental vertical can be no closer 
than about 6 feet from the center of the existing radial field. (for 
purely structural reasons).

I tried using EZNEC, but as all I have is the "el cheap-o" version 
that comes free with the ARRL Antenna Book, this is not an option for me.

Any info?

Charles - K5ZK