Paradigm Lost: Nikola Tesla's True Wireless Page 15

the use of Naval Electricians, published in 1918, contains the following diagram showing the direction of electric lines (see Fig. 10).⁴¹ It illustrates that a monopole antenna radiating above a flat perfectly conducting ground tends to radiate in a direction parallel to the ground and not in a direction along the axis of the antenna. This is not a polar plot of the field strength vs. angle but a picture showing the direction of the electric field at various locations. Incidentally, one can argue that there is no radiation along the axis of the antenna even if the ground has imperfect conductivity.⁴²

Tesla specifically condemns any theory that claims “[space waves] pass along the earth’s surface and thus affect the receivers. I can’t think of anything more improbable than this ‘gliding wave’ theory which… [is] contrary to all laws of action and reaction.” Of course, this gliding wave concept that we would now call a “surface wave” did describe daytime radio propagation and was central to the work of such theorists as Sommerfeld, Zenneck, and Watson.⁴³

Tesla Debunks the Ionosphere

Warming to the task of diminishing other theorists, Tesla then damns what was then only a conjecture: the belief in what was then known as the Kennelly-Heaviside layer. We now call this the ionosphere — a set of layers of three or more ionized gases in the earth’s upper atmosphere. It was first postulated, as a single layer, in 1902 by Arthur Kennelly and Oliver Heaviside, working independently, as a way of explaining how radio waves propagate beyond the horizon.⁴⁴ Although its existence and height were not verified experimentally until 1924 by the Englishman Edward Appleton, for which he was later awarded the Nobel Prize, its presence was generally accepted in 1919, especially as a means to explain the long distances that radio waves would propagate at night.⁴⁵ Tesla tells us, “I have noted conclusively that there is no Heaviside layer, or if it exists it is of no effect.” One wonders if he recanted this statement after Appleton’s experiment.

Communication with Airplanes

Among the more perplexing aspects of Tesla’s article is his discussion tied to his Fig. 15. He is showing here in Fig. 11 a “Hertz oscillator” suspended in the air, and uses this arrangement to explicate something that became well known during World War I: an airplane could communicate with a wireless receiver on the ground. Also known, but not discussed by Tesla, was that two airplanes in the air might experience radio contact with each other.