[BC] Kinstar vertical radiation patterns

[Dan Strassberg]

Looking through Louis duTreil's paper last night--and specifically at the
figures that show vertical radiation patterns, one thing stood out: The
high-angle radiation--from about 70 degrees to 80 or 85 degrees above the
horizon--seems to be significantly greater than that of a standard
1/4-wavelength radiator.

This seems to suggest that the fading properties within a station's 0.5 mV/m
contour would be noticeably worse than those of a standard 1/4-wave tower.
There is no high-angle lobe as with antennas greater than 180 degrees, but I
would think the community of owners, engineers, and consultants who are
welcoming the Kinstar development as a key element in the potential
salvation of AM would want a lot more information about the performance of
real-world installations.

Also, Kintronics' Web site touts heights of 0.05 wavelength as being quite
satisfactory for Kinstar antennas, whereas duTreil talks mainly about 0.08
wavelength. It also appears that the biggest difference between 0.05- and
0.08-wavelength Kinstars is the shorter antenna's lower driving-point
impedance. As long as suitable matching networks can be constructed for the
lower impedance, I guess this difference will turn out to be unimportant.
But if 0.08-wavelength really proves necessary, a lot of Kinstars will
require real towers, as opposed to utility poles, and because of NIMBY
protests, the antennas will prove useful mainly only for stations at
frequencies above about 1100 kHz.

Lastly, I was fascinated by the simulation of a three-element in-line DA in
which the two end elements didn't require top loads extending perpendicular
to the array axis. Can anyone explain why only the center element required a
"full" top load?

--
Dan Strassberg, dan.strassberg at att.net
eFax 707-215-6367