On Sat, 31 Mar 2007 07:23:23 -0700, dansawyeror
wrote:

Which portion of this antenna is the radiator? Is it the portion below
the coil or the entire antenna?

Hi Dan,

To be precise, EVERYTHING is the radiator. The unchoked line, the
vertical to the coil, the coil, the whip above the coil, AND the
radials.

What is of concern, is what is called the current node (I'm about to
embrace that tarbaby called standing waves) whose placement can have a
very significant impact on the directivity (another tarbaby of "gain"
raises its prospect here) of the antenna.

The higher the coil resides in the vertical element, the more linear
distance beneath it is available to that current node, and from this,
a greater signal out. There is a point of diminishing return (an
economics term, not a radiation term) where raising the coil ever
higher brings no further gain (both a pun to fulfill the economic
basis, and a literal result of RF). You can reclaim more gain from a
high coil by adding a top hat which serves to extend the whip above
the coil. Hence there is a generally acknowledged rule of thumb that
the coil resides somewhere between one half way up to two-thirds the
way up of a simple vertical. You may note that your antenna attempts
to conform to this model in some sense (for instance, it is not a base
loading which is the poorest configuration).

73's
Richard Clark, KB7QHC