Topband: Top loading

[Henry G. Elwell, Jr.]

This Reflector is a fountain of knowledge, so I want to dip
into it again with a question that I and others have found
confusing; top loading and ground losses.  As someone said,
"You can't always believe the story books."

	In September 1971 when I was W2MB, Ham Radio published an
article by me on a top loaded vertical for 80 meters: it
applies to 160 meters.  The antenna was 1/4 wave in length,
with a six foot diameter, multi-wire disc at the top, and
directly underneath was an inductance.  The disc and
inductance were tuned to 80m. A #12 wire, 60 ft long had 2v,
60 ma. bulbs soldered every five feet along the wire, and
each bulb was tapped five inches across the wire.

	Before connecting the top loading, to get a reference, the
antenna was excited at night with 1 kw input to the driving
amplifier. The bulbs lit, with the base lamp brightest, with
decreasing brilliance to a no-lit bulb at the top; high
current at the base as expected.

	The top loading was then connected, and the test repeated.
(Usual experimental problems are covered in the article) 
The lamps now reversed their brilliancy, with the bottom
lamp not lit, and the brightest lamp being at the 80-85% to
top level position. The top bulb next to the inductance was
of slightly less brilliancy.  The pattern was essentially
that of a half wave antenna, probably with a lamp of zero
brilliancy. if I had one, at the top side of the top
loading. 

	QUESTION:

	1. Did that antenna have less ground loss than the non-top
loaded vertical?

	2. If yes, did it make radials of less importance?

	Please reply to elwell@salisbury.net and I'll summarize if
there is enough interest.

Vy 73, Henry
Henry G. Elwell, Jr., N4UH



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