Topband: K9AYLoop Grounding

[K9AY]

> The consensus for grounding Beverages seems to be to use a "real
> transformer" and have isolated grounds for the antenna and the coax.
>
> Does the same apply to the K9AY antenna? Has anybody tried it both
> ways and seen a difference?
>
> Paul - KW7Y

Paul,

The commercial units we make do not have an isolated ground.  In theory, an 
isolated ground would minimize the potential of common-mode problems, but in 
my experience, that potential is very small with moderate length, buried or 
on-ground cables.

I would recommend feedline isolation in the following extreme 
circumstances -- extremely poor ground (e.g. desert sand), very long 
feedline and control line, feedline that must cross the TX radials, and 
feedline that is elevated above ground for a portion of its length. That 
isolation can be 1) transformer with separate primary and secondary, 2) 
ferrite beads, 3) coiled feedline, perhaps through a toroid, or 4) feedline 
buried for at least a portion of its length.

Finally, do no confuse re-radiation and common-mode -- signals re-radiated 
by the TX antenna, other towers, or nearby metal are received directly by 
the antenna. This is more likely to be an issue with a K9AY Loop, since it 
may be installed near potential re-radiation sources.

73, Gary
K9AY