On Wed, 26 May 2004 14:10:01 GMT, "Henry Kolesnik"
wrote:

Is there a homebrew instrument that I can make that will let me know when
I'm out of the near field and in the far field? I'd like it to work with
mobile whips as well as dipoles on HF. The ARRL Ant HBK formula for the
boundary D between the two fields is an approximation where D = 2L^2/w where
L is ant length in same units as w, the wavelength.
tnx

Hi Hank,

That is an interesting question. So right off the top I will admit I
know of no such beast. However, the formula looks particularly
liberal. Normalized it appears to suggest for a common dipole that
distance would be 1 wavelength, but I would think it from the
literature that this distance would be closer to 5. It is all a
matter of degree in how thin you want to cut it.

At:
http://home.comcast.net/~kb7qhc/ante...elds/index.htm
I have done a suite of 6 antennas and have illustrations of the near
field in terms of its Z expressed as SWR to free space. If nothing
else this will give you a picture (for what it's worth). In returning
to the delineation between near and far, my illustrations show only
the first quarterwave out and things have pretty well settle out in
this scale.

73's
Richard Clark, KB7QHC