Richard Harrison wrote:
. . .
According to J.D. Kraus, radial conductor ground-plane antennas were
originated by G.H. Brown. Story is that Brown said only two radials were
needed (for equilibrium?). RCA`s marketing department insisted on four
and that`s how it`s been ever since.

That's a true story, also related in Brown's autobiography _And Part of
Which I Was_. Two radials are necessary for near cancellation of their
fields, to allow a circular pattern. The marketeers felt that it didn't
look symmetrical enough to be marketed as an omnidirectional antenna so
insisted on adding two more.

Two radials produce a very circular pattern in a directly horizontal
direction. The pattern becomes non-circular above and below horizontal,
but only very slightly for moderate angles above and below. I took
advantage of knowing that story when I was asked not long ago to design
an omnidirectional antenna to go in a small essentially flat volume. It
ended up as a variation of a ground plane with two radials, implemented
as flat traces on a PC board substrate. I built a prototype with copper
tape and had it measured in an anechoic chamber at a test lab. It had
the most circular pattern the lab technicians had ever seen, better than
their very expensive reference antenna. The extreme quality of the
circularity was actually a lucky coincidence because there are factors
such as feedline coupling which cause some variation even in a lab
environment. But it left no doubt that the pattern circularity was in
fact very good in spite of the apparently asymmetrical construction.
Brown was right.

George Brown, one of the pioneers of television, was also the inventor
of the turnstile antenna, widely used for TV broadcasting. And he's the
Brown of Brown, Lewis, and Epstein's seminal paper on radial ground
systems. He also had a legendary sense of humor. One of his most famous
stunts was substituting a blue-dyed banana for the yellow one in a bowl
of fruit used to test the first color TV broadcast, causing a great deal
of head-scratching among the engineers at the other end trying to figure
out what was wrong with the color transmission. Walt Maxwell, W2DU,
worked with Brown at RCA.

Roy Lewallen, W7EL