[Lowfer] Distance from powerline question

[JD]

There is no magic number, Andy.  Even the traditional definitions of near 
field and far field are only vague approximations in a real-world system 
with all the variables that a power grid presents.  Not to mention, those 
definitions are also frequency dependent...both in terms of what is being 
emitted from the power line as noise, and what signals it is (in effect) 
shielding from reaching nearby antennas.

It requires experimentation to determine a satisfactory LF receive antenna 
location in any case...but one reasonably useful rule of thumb is to 
determine the height of the nearest power line or other conductive 
structure, and keep the antenna _at least_ that far removed from it.

This will obviously limit horizontal runs on most residential properties! 
But unless one has sufficient room for a wave antenna to begin with, one 
should be thinking height rather than length wherever possible anyway.  For 
a wire antenna at LF, it's the vertical portion that intercepts the useful 
signal--hence the popularity of active whips--whereas the horizontal 
portion, if any, serves only to increase capacitance to ground for tuning 
and matching purposes.  That's good when the antenna is in the clear, but 
not so much when power lines or other conductors are around.

John