Nikola  Tesla:  The  Guy  Who  DIDN'T  "Invent  Radio"

Thomas H. White -- November 1, 2012

It can be intimidating -- the assertion that it is a "settled fact" that "Nikola Tesla was the real inventor of radio". Below are some thoughts about this all too widely believed myth.
Don't try this at home!
Composite picture of Tesla
I call this the "Dum-de-dum! Look at me, Nikola Tesla, calmly sitting amidst the big sparks from my big spark machine" photograph. Although the sparks (circa 1899) are real, widely distributed photographs like this were essentially fakes -- the polite description is that the photograph is "a composite" -- because Tesla's image was added separately. Actually sitting this close to huge sparks risked a medical condition known as "death". I do not know why Tesla decided he needed to embellish the picture and issue it to an unsuspecting public. But tricks like this helped convert his reputation from legitimate experimenter to publicity-hungry showman. (One performer inspired by Tesla was Electrice, the Girl Who Defies Electricity).

Question: Shouldn't Nikola Tesla be considered the "inventor of radio", given that in 1943 the United States Supreme Court (supposedly) overturned all of Guglielmo Marconi's patents and proclaimed Tesla "the true inventor"?

Gut Reaction: Are you joking??? In no way, shape or form can this guy be considered the "inventor of radio". Furthermore, contrary to what you might have read, the U.S. Supreme Court never said that he was -- not in 1943, not in any other year. If fact, if anything Tesla's "contribution" was to confuse and slow radio development, due to his misunderstanding of the physics involved. Fortunately, at the time few people were listening to his misguided and exaggerated "true wireless" ramblings.

A More Dignified Response: A fuller answer is that although Tesla did do groundbreaking research in early electrical systems, most importantly wired power transmission using alternating current, his contributions to radio technology were minimal, overshadowed by the far more important practical work conducted by other inventors and scientists, including Heinrich Hertz, Oliver Lodge, Guglielmo Marconi, Karl Braun -- the latter two shared the Nobel prize for physics in 1909 -- Reginald Fessenden and John Stone Stone. And about that 1943 Supreme Court ruling -- Marconi Wireless Tel. Co. v. United States - 320 U.S. 1 -- this case actually did NOT even try to determine "who invented radio". Instead, it just set governmental compensation for the use of patents primarily during World War One -- not the original patents covering radio transmission and reception, but ones covering later improvements. One of these improvements was using an adjustable "four-circuit" transformer configuration for radio transmission and reception. And in this matter, the U.S. counterpart to Marconi's original British "four sevens" tuning patent was in fact invalidated. But, instead of awarding priority to Tesla, the court actually upheld a 1935 lower court ruling that Oliver Lodge's -- and especially John Stone Stone's -- earlier work and patents had priority. So, to recap, the 1943 decision didn't overturn Marconi's original patents, or his reputation as the first person to develop practical radiotelegraphic communication. It just said that the adoption of adjustable transformers in the transmitting and receiving circuits, which was an improvement of the initial invention, was fully anticipated by patents issued to Oliver Lodge and John Stone Stone. (This decision wasn't unanimous, but the dissents sided not with Tesla, but with Marconi.)

In fact, it is bizarre to even claim Tesla "invented radio", since, as described below, at least through 1919 he didn't even believe that radio waves existed, or that any form of what he called "longitudinal space waves" could be used for long-distance communication. Instead, he had his own unworkable idea of what constituted "the true wireless", believing that alternating electrical currents somehow could be injected into the ground to provide, not just communication, but also electrical power "around the world".

Interesting Trivia: The syllabus at the beginning of the 1943 U.S. Supreme Court decision provides a summary of the ruling. There are thirteen sections. None mentions Tesla.

About  that  1943  U.S.  Supreme  Court  Decision

Nikola Tesla 1857-1943 (famous)
John Stone Stone 1869-1943 (not so famous)
To repeat, the 1943 Supreme Court case never made any sort of ruling as to "who invented radio", nor did it ever intend to. Instead, it was a financial compensation case, covering later technical improvements which were patented a few years after Marconi had first demonstrated long-distance radiotelegraphic communication.

During World War One, in order to support the war effort, the U.S. government knowingly infringed on numerous radio patents, while promising to provide compensation after the conclusion of the conflict. After the war ended, an Interdepartmental Radio Board was formed to provide advice -- included in the outstanding legal tangles was an American Marconi suit filed July 29, 1916. On May 31, 1921, a Board report recommended awards totaling $2,869,700.27 to fourteen firms, including $1,253,389.02 for four patents (pared down from the initial claim of 350) that had been controlled by the Marconi Wireless Telegraph Co. of America. (Neither Tesla nor John Stone Stone were included in this recommendation -- this background information is provided by The Navy and the Patent Situation chapter of Captain Linwood S. Howeth's History of Communications-Electronics in the United States Navy). However, the U.S. Congress declined to follow the board's recommendation, and instead told the affected companies and individuals they would have to follow the normal procedure of suing the U.S. government for damages, through the Court of Claims.

In 1919, most of American Marconi's assets had been sold to General Electric, which used them to form the Radio Corporation of America. But, hoping for a million dollar windfall, the stockholders of American Marconi pressed forward with a lawsuit, primarily for compensation for the infringement of patent No. 763,772, which was the U.S. version of Marconi's British "four sevens" tuning patent. The Marconi company had a long history of winning similar suits, both in the U.S. and other countries. In particular, in 1914 the company had won an important case against the National Electric Signaling Company, as a District court upheld both Marconi's original U.S. radio patent and his later tuning patent. (That ruling found Tesla's activities to be unrelated to radio communication, declaring that "in 1893 Tesla reverted to the impracticable scheme of electrostatic induction". A period example of this was an 1897 Electrical Review report, which noted that Tesla proposed to signal for long distances by varying the planet's "electrostatic equilibrium").

But one consistent pattern with these legal entanglements was they had ignored a tuning patent, No. 714,756, issued to John Stone Stone in 1900, prior to Marconi's tuning patent, apparently because individuals claiming they weren't infringing Marconi's patent didn't see any advantage in saying they were really infringing Stone's.

Irony Alert: Stone testified as an expert witness in a number of early patent infringement cases, some of which included tuning, but was never called upon to discuss his own tuning patent. Stone had organized one of the first radio companies, and assigned his patents to it. However, after a small number of installations, primarily for the U.S. Navy, the company went bankrupt, and in 1913 its assets went into receivership, to be sold to compensate the bondholders, so there never had been any organized corporate defense of the Stone tuning patent. Double Irony Alert: While Stone's company was active, it adopted a receiver design that blatantly infringed Fessenden's electrolytic patent, so perhaps that was an extra incentive not to stir up the legal system.

In 1915, American Marconi had sued the Atlantic Communications Company for patent infringement -- this suit incidentally pitted Marconi against his 1909 Nobel prize co-winner Karl Braun. And for the first time Stone joined the legal fray, in support of the defense, in order to promote his own tuning patent. It is likely a decision would have resulted in the court recognition that he wouldn't get until 1935. However, the outbreak of World War One in Europe caused the case to be suspended as Marconi returned to his native Italy to support the Allied cause. Later, the United States entered the war on the Allied side, and the government seized the Atlantic Communications Company assets as enemy (German) property, so this legal case was never concluded.

In the Court of Claims compensation case (this was the case reviewed in 1943 by the Supreme Court), the U.S. government brought up Stone's largely forgotten patent in its defense, and in 1935 the court upheld the contention that the Stone patent had priority over Marconi's. (According to his biographer, a gratified Stone wrote that "the Court of Claims had declared him to be the inventor of coupling, and as letters of his at the time show, he took this for permanent acclaim".) The American Marconi side -- stubborn to the end and not used to losing -- appealed this decision, but eight years later the Supreme Court came to the same conclusion.

Since this was a patent case, the opinions make for complex reading. But, overall, the Marconi plaintiffs fared badly with the Supreme Court's decision. They were denied any compensation for Fleming's two-element vacuum-tube patent, because the court ruled it had been improperly granted, thus was invalid. In addition, sustaining the 1935 decision by the Court of Claims, the court ruled against the Marconi side on almost all of the claims for Marconi's tuning patent. Again, there are two important facts to remember about the 1943 ruling -- the case was not about Marconi's initial invention of a practical system of radiotelegraphy, but instead covered a later refinement -- variable four-circuit tuning. And although Marconi's tuning patent was overturned, it was not because of Tesla, but because of Stone's and Lodge's priority.

The idea that somehow this case was "a great victory for Tesla" ignores clear and definitive statements in the ruling to the contrary. For example, from Justice Frankfurter's dissenting opinion on the tuning patent, which sided with Marconi (but NOT Tesla):
The inescapable fact is that Marconi in his basic patent hit upon something that had eluded the best brains of the time working on the problem of wireless communication--Clerk Maxwell and Sir Oliver Lodge and Nikola Tesla. Genius is a word that ought to be reserved for the rarest of gifts. I am not qualified to say whether Marconi was a genius. Certainly the great eminence of Clerk Maxwell and Sir Oliver Lodge and Nikola Tesla [320 U.S. 1, 63] in the field in which Marconi was working is not questioned. They were, I suppose, men of genius. The fact is that they did not have the 'flash' (a current term in patent opinions happily not used in this decision) that begot the idea in Marconi which he gave to the world through the invention embodying the idea. ... And yet, because a judge of unusual capacity for understanding scientific matters is able to demonstrate by a process of intricate ratiocination that anyone could have drawn precisely the inferences that Marconi drew and that Stone hinted at on paper, the Court finds that Marconi's patent was invalid although nobody except Marconi did in fact draw the right inferences that were embodied into a workable boon for mankind. For me, it speaks volumes that it should have taken forty years to reveal the fatal bearing of Stone's relation to Marconi's achievement by a retrospective reading of his application to mean this, rather than that.

However, the majority opinion found priority for Stone and Lodge (again, NOT Tesla):
Marconi's reputation as the man who first achieved successful radio transmission rests on his original patent, which became reissue No. 11,913, and which is not here in question. That reputation, however well deserved, does not entitle him to a patent for every later improvement which he claims in the radio field. Patent cases, like others, must be decided not by weighing the reputations of the litigations, but by careful study of the merits of their respective contentions and proofs. As the result of such a study, we are forced to conclude, without undertaking to determine whether Stone's patent involved invention, that the Court of Claims was right in deciding that Stone anticipated Marconi, and that Marconi's patent did not disclose invention over Stone.

[Footnote 18] It is not without significance that Marconi's application was at one time rejected by the Patent Office because anticipated by Stone, and was ultimately allowed, on renewal of his application, on the sole ground that Marconi showed the use of a variable inductance as a means of tuning the antenna circuits, whereas Stone, in the opinion of the Examiner, tuned his antenna circuits by adjusting the length of the aerial conductor. All of Marconi's claims which included that element were allowed, and the Examiner stated that the remaining claims would be allowed if amended to include a variable inductance. Apparently through oversight, Claims 10 and 11, which failed to include that element were included in the patent as granted. In allowing these claims the Examiner made no reference to Lodge's prior disclosure of a variable inductance in the antenna circuit.

Marconi's patent No. 763,772 was sustained by a United States District Court in Marconi Wireless Telegraph Co. v. National Signaling Co., 213 F. 815, and his invention as specified in his corresponding British patent No. 7777 of 1900, was upheld in Marconi v. British Radio & Telegraph Co., 27 T.L.R. 274, 28 R.P.C. 18. The French court likewise sustained his French patent, Civil Tribunal of the Seine, Dec. 24, 1912. None of these courts considered the Stone patent or his letters. All rest their findings of invention on Marconi's disclosure of a four-circuit system and on his tuning of the four circuits, in the sense of rendering them resonant to the same frequency, in both of which respects Stone anticipated Marconi, as we have seen. None of these opinions suggests that, if the courts had known of Stone's anticipation, they would have held that Marconi showed invention over Stone by making the tuning of his antenna circuit adjustable, or by using Lodge's variable inductance for that purpose.

As far as I can tell, claims that the 1943 Supreme Court case in some way declared Tesla to be "the inventor of radio" didn't start to appear until the next decade -- I have not found any contemporary reviews of the ruling which even remotely suggested that the case was seen as a major recognition of Tesla, or that it "overturned all of Marconi's patents". And, frankly, I don't have the slightest idea how anyone could interpret this case as doing anything more than reviewing Tesla's work while discussing the history of electrical tuning prior to the development of radio communication. The closest analogy I can think of would be claiming that in the case of Bush v. Gore, the Supreme Court ruled that Pat Buchanan had been elected President of the United States. Yes, he was mentioned. No, he was not the victor.

Irony Alert: In 1944, John J. O'Neill published the comprehensive and extremely laudatory Prodigal Genius: The Life of Nikola Tesla. However, the author doesn't mention the 1943 Supreme Court case and doesn't claim that any court had proclaimed Tesla to be "the inventor of radio". In fact -- after inaccurately describing Tesla's work as "radio" and overstating its applicability to modern communications systems -- he even laments that "The system invented and discovered by Tesla is the one in use today; but who ever heard anyone giving Tesla the slightest credit?"

In marked contrast, there were contemporary references that John Stone Stone had finally received the recognition he had long deserved for his tuning patent. For example, a tribute by Lee De Forest that appeared shortly after Stone's death included the following:
    By the irony of fate Stone's death occurred less than one month before the Supreme Court of the United States, in a historic decision handed down June 21, 1943, announced the invalidity of the once famed "four-tuned circuits" patent of Marconi.
    In view of the court's sweeping decision, concurred in by all but two Judges, it is indeed to be regretted that John Stone could not have lived to witness this long-belated official recognition of his well-merited claim to have preceded Marconi in this all-important invention, so vital to radio communication. -- Lee De Forest, Proceedings of the Institute of Radio Engineers, September, 1943, page 522.

(Tesla's obituary, in the May, 1943 issue of the same journal, far from declaring him the "inventor of radio", instead diplomatically noted that his "theory of the transmission of radio-frequency energy is at variance with that now accepted". Meanwhile, the February, 1943 Power Plant Engineering commented "His obituary notices in the newspapers referred to him as the 'electrical genius who discovered the fundamental principle of modern radio.' As a matter of fact this is not true. Poor old Tesla had very little to do with the discoveries of the fundamentals of radio, but in his early days he experimented with the production of high frequency currents and because his oscillation transformer, generally known as the Tesla coil, produced spectacular effects, he became known as a wizard. A legend developed about him which was kept alive by the imaginations of newspaper men. ... In his development of the Tesla coil, Nikola Tesla produced a device which produced extremely high voltage high-frequency currents and these produced startling effects. Apparatus of this kind was seen in electrical and physics laboratories for many years, but it never served any really useful purpose.")

A short time after the Supreme Court ruling was issued, Orrin E. Dunlap compiled Radio's 100 Men of Science, providing "Biographical Narratives of Pathfinders in Electronics and Television". Apparently unaware that the Supreme Court had supposedly recognized Tesla's priority, Marconi's entry is titled "Inventor of Wireless". (John Stone Stone's section is "Sharpened the Wireless Tuners", while Tesla's gets the more nebulous title of "Genius Was Applicable to Him".) The only reference in the biographical sections to the 1943 case appears as a footnote in the Marconi review, and it documents John Stone Stone's recent recognition:
Supreme Court of the United States on June 21, 1943, delivered an opinion in the case of the Marconi Wireless Telegraph Company of America vs. the United States invalidating Marconi's American patent No. 763,772 on four-circuit tuning. The Court based its decision largely on finding that John Stone Stone's patent, applied for February 8, 1900, was nine months prior to Marconi's application for his American patent that covered tuning. Stone's patent was allowed February 2, 1902. Marconi's was granted June 28, 1904. It was the equivalent of his famous British patent No. 7,777 on tuning granted April 26, 1900. -- Orrin E. Dunlap, Radio's 100 Men of Science, 1944, page 175.

In 1946, Donald McNicol (previous president of the Institute of Radio Engineers) published Radio's Conquest of Space, reviewing "The Experimental Rise in Radio Communication". Not only did he not credit Tesla as radio's inventor, he even went so far as to say:
It has already been stated that one of the books read by Marconi in 1894 or 1895, when he was twenty years of age and seeking knowledge of high-frequency electric phenomena, was a book by Martin [The Inventions, Researches and Writings of Nikola Tesla] dealing with Tesla's researches in America. A search through this work to locate text that might have been of value or suggestive to Marconi does not bring to light anything which could have been of value or suggestive to the young Italian if he was thinking of wireless signalling. ...
   There is no escaping the conclusion that Tesla had not fully grasped the main point of Maxwell's message. ...
   Tesla's conception of the direction which "wireless" research should take is hinged upon this 1893 pronouncement with respect to "disturbing" the electrical conditions of the earth, and it was this dominant idea which drove him to the spectacular experiments carried on by means of Brobdingnagian towers erected at great expense on Long Island, New York, and on Pike's Peak, Colorado. At great expense, it was said, to a venturesome captain of industry. So far as practical results are of interest this series of experiments proved unprofitable. -- Donald McNicol, Radio's Conquest of Space, 1946, pages 43, 54, 55-56.

To expand on McNicol's comments, he wasn't saying that Tesla hadn't done valuable work, just that it wasn't applicable to Marconi's original radiotelegraph system. It is sometimes misstated that Marconi's early equipment -- a simple spark-gap transmitter and coherer receiver -- was heavily influenced by, or even a direct copy, of Tesla. But Marconi's original transmitter was clearly based on Hertz's basic design using a Rhumkorf spark coil, as improved upon by Augusto Righi, and the coherer receiver in turn was an improved version of Edouard Branley's. Besides being wrong, this is something of an insult to Tesla, since at the time he was designing sophisticated industrial electrical power equipment, while Marconi was essentially a tinkerer using homemade devices. (For example, in Figure 11 of "The True Wireless", Tesla himself contrasted Marconi's original simple radiotelegraph equipment ("Hertz Wave System") with his own patent ("Tuned Wireless System") for proposed ground-current power transmission. In fact, after Marconi applied for his first patent issued in Britain in June, 1896, the controversy was actually over how similar his equipment was to that demonstrated by Oliver Lodge in 1894). But, primitive as it was, it was Marconi who made history, by showing that radio signals could be used for long-range wireless communication.

In 1946, radio engineer George H. Clark published a biography of The Life of John Stone Stone. (Clark was a radio historian, whose collection of materials comprise the bulk of the Radioana collection located at the Smithsonian Institution's Lemelson Center for the Study of Invention and Innovation.) Clark certainly had no doubts about the 1943 ruling being recognition of John Stone Stone. In a chapter titled "Vindication", he wrote:
    The U.S. Court of Claims declared the Marconi patent invalid, and having been anticipated by Stone's patent No. 714,756. One claim was excepted, on a matter not pertinent to this story. The United States Supreme Court, to which this case was appealed, upheld this finding in its decision of June 21, 1943...
    And thus, after forty-one years, when the Stone Company had been long forgotten and after the gallant patentee himself had gone to eternal rest, his patent came to life again, and vindicated the high vision of it's creator. -- George H. Clark, The Life of John Stone Stone, 1946, pages 131-132.

In his 1950 autobiography, Father of Radio, Lee DeForest again reviewed the 1943 Supreme Court case. Although he mentions Tesla in passing when reviewing the tuning decision, he clearly thought that Stone's work had been found to be far more important than Tesla's:
    By the irony of fate Stone's death occurred less than one month before the Supreme Court of the United States, in a historic, decision handed down June 21, 1943, announced the invalidity of the once famed "four-tuned circuits" patent of Marconi. This was the Marconi patent that almost stopped the American De Forest Wireless Telegraph Co. in 1905. The belated decision was therefore especially interesting and gratifying to me.
    In coming to its decision, the Court laid especial emphasis on the early work of Stone and Tesla, particularly the Stone patent No. 714,756, applied for nine months prior to Marconi's and allowed February 2, 1902, a year and a half before the grant of Marconi's patent. This, the Court said, "showed a four-circuit wireless telegraph apparatus substantially like that later specified and patented by Marconi. It described adjustable tuning of the closed circuits of both transmitter and receiver, with antenna circuits so constructed as to be resonant to the same frequencies as the closed circuits."
    The Court points out Stone's emphasis on "loose coupling," the first in the art so to do. Quoting freely from the Stone patent, the Court adds -- "These statements sufficiently indicate Stone's broad purpose of providing a high degree of tuning at sending and receiving stations," and "Stone's full appreciation of the value of making all of his circuits resonant to the same frequency. Stone showed tuning of the antenna circuits before Marconi, and if this involved invention, Stone was the first inventor." -- Lee DeForest, Father of Radio, 1950, pages 456-457.

The most famous radio engineer in the period from the late 1910s through the mid-1950s was Edwin Howard Armstrong, best known for the development of the superheterodyne receiver and FM radio, among many other achievements. And he had no doubt about Marconi's priority in the initial development of radiotelegraphy:
    Had Marconi been more of a scientist and less of a discoverer, he might have concluded that his critics were right, and stopped where he was. But like all the discoverers who have pushed forward the frontiers of human knowledge, he refused to be bound by other men's reasoning. He went on with his experiments; and he discovered how, by attaching his transmitted waves to the surface of the earth, he could prevent them from traveling in straight lines, and make them slide over the horizon so effectively that in time they joined the continents of the world. Several years were to pass before agreement was reached on the nature of Marconi's great discovery, though Marconi himself understood very well how to apply it and to employ it usefully; and it proved to be the foundation upon which the practical art of wireless signaling was built.
    Marconi's claim to the invention of wireless telegraphy is beyond challenge. -- Edwin Howard Armstrong, Wrong Roads and Missed Chances, 1951, reprinted in The Legacies of Edwin Howard Armstrong, page 289.

(In an obituary which appeared in the April, 1943 The Scientific Monthly, Armstrong noted that Tesla had met with failure due to "following an erroneous theory" to "disturb 'the charges of the earth'", compounded by the fact that he failed to conduct further experiments which "might well have led to the discoveries which later were made by Marconi".)

Okay then, what about this century? Surely by now everyone "knows" that it was Tesla who invented radio, right? Well, in Sungook Hong's historical review, Wireless: From Marconi's Black Box to the Audion, published by the Massachusetts Institute of Technology Press in 2001, the author was unconvinced:
    In the US, Tesla undoubtedly thought about possible ways of using rapid oscillation for signaling in the early 1890s. Tesla's admirers claim that Tesla demonstrated message transmission by means of Hertzian waves for the first time in 1893 in his St. Louis lecture. This claim is, however, not supported by any direct evidence, and the fact that Tesla used a Geissler tube as a detector (how could one effectively detect Morse-coded signals with the Geissler tube?) strongly weakens the claim. In addition, his ideas about how signals are communicated through space were similar to earth-conductive (wireless) telephony, rather than Hertzian wireless telegraphy. For the Tesla-first claim, see Cheney [Tesla: Man Out of Time 1981], pp. 68-69. Compare Cheney's claim with Tesla's original, unclear ideas (Tesla 1894 [The Inventions, Researches and Writings of Nikola Tesla], esp. pp. 346-349). See also Anderson [Priority in the Invention of Radio: Tesla vs. Marconi] 1980. -- Sungook Hong, Wireless, 2001, page 199.

That same year, Professor of Electrical Engineering Paul J. Nahin was even more emphatic in his book, writing in a sidebar of The Science of Radio:
    One other person whose name is occasionally put forth as the inventor of radio is Nikola Tesla (1856-1943), who was born in Croatia and later became a naturalized American citizen. Tesla's was an intuitive, erratic personality, and his rightful fame among electrical engineers is for the discovery of the rotating magnetic field principle behind the synchronous ac induction motor. He was also a force in the early development of multi-phase ac power distribution. The unit of magnetic flux density is named after him. Others, however, not satisfied with Tesla's true achievements, find it necessary to claim he did all sorts of other things as well (which, curiously, not even the full scientific might of the Pentagon can duplicate, such as Tesla's famous 1934 'radio death ray' that he said could destroy 10,000 planes 250 miles away and annihilate, in an instant, an army of 1,000,000). It seems more likely that Tesla, unable to repeat his early triumphs, looked for other ways to get back into the limelight he so coveted; he began to make astonishing claims to wealthy potential patrons who, knowing next to nothing of science, could be easily dazzled. One of these claims was that he had "invented radio." Tesla was, without question, very skillful at generating large, noisy sparks with the aid of step-up transformers tuned to resonance (the famous Tesla coil) and he seems to have really believed that, since Marconi used sparks in his wireless work, then he too must be a wireless pioneer. There is, however, not a shred of credible evidence that Tesla did anything more than just talk about radio (in 1901, for example, he claimed that two years before he had received radio signals from Mars), and nothing in the historical record supports his grandiose claims. It is clear, in fact, from what he did write, that Tesla actually had only the slightest (if that) understanding of electromagnetic radio physics; he claimed, for example, that "his" electric waves were both immune to the inverse-square law and that they traveled faster than light. Tesla does appear to have sincerely believed his own outrageous statements; he lived in a delusional world of self-aggrandizement that became increasingly cut off from reality. His only human joy seems to have been feeding the pigeons of New York City, where he died in a hotel room a lonely, bitter man. Modern biographers of Tesla (none of whom have any technical training) continue to muddy the historical record, however, and so let me be quite clear Tesla did not invent radio, although his flowery talk about it no doubt inspired many youngsters at the start of the twentieth century to become interested in "the new wireless." -- Paul J. Nahin, The Science of Radio, 2001, pages 9-10.

Even today, the National Inventors Hall of Fame is under the impression that "Marconi's radio was the first to demonstrate workable wireless radio communication." And the National Association of Broadcasters annually recognizes outstanding achievements with Marconi Awards.

Interesting Trivia: John Stone Stone admired Nikola Tesla -- reviewing Tesla's early work with high-frequency currents, he testified that Tesla's investigation of "alternating current phenomena... did more to excite interest and create an intelligent understanding of these phenomena in the years 1891-92-93 than anyone else". In turn, Tesla admired John Stone Stone, stating at his acceptance of the 1916 Edison Medal that Stone was a person "whom I consider, if not the ablest, certainly one of the ablest living experts". However, in the mid-1910s Stone was guilty of being overly effusive while praising Tesla, by crediting Tesla with being vastly more influential and knowledgeable about early radio development than was really the case. It appears that what happened was that Stone projected his own extensive and accurate knowledge about radio signalling onto Tesla. However, if it was Stone's intent to move his friend into the physics and engineering mainstream, it proved unsuccessful, for a few years later, in "The True Wireless", Tesla contradicted most of what Stone had said he believed, and showed how misguided he actually was. This would be far from the last time that an admirer would give far more credit to Tesla than was actually due. It also highlights the need to carefully review Tesla's actual words, rather than what an enthusiastic admirer wished he said or believed. Nota Bene: Sometimes, when repeating Stone's comment about Tesla, the qualifier in the years 1891-92-93 is edited out, making Tesla appear more influential than Stone actually stated. And while we are at it, it is also common, when referring to the quote from the 1943 Supreme Court case that says Marconi's "reputation, however well deserved, does not entitle him to a patent for every later improvement which he claims in the radio field", to omit the subsequent clarifying phrase "the Court of Claims was right in deciding that Stone anticipated Marconi", in order make it appear that instead of Stone, it is Tesla being referenced by this statement.
ngram comparison of Tesla and Stone references
John Stone Stone was best known for promoting "one-wavedness" -- employing the "loose-coupling" of transformers so that transmissions were sent on a single radio frequency, avoiding the "double-hump" of two frequencies which resulted when the transformers were arranged too closely together. Historic references to Stone also are "one-wave", peaking around the time of his death and the 1943 Supreme Court decision.

Informative Anecdote: A college classmate attended what appeared to be a standard supplementary physics lecture. Unfortunately, the lecturer turned out to be a community local, sharing his own unique ideas about reality. The "lecture" opened with the claim that, contrary to its long-accepted value of 3.14159 etc., pi was actually equal to exactly 3. His audience evaporated at this point, although at the time I thought it might have been interesting if they had stayed awhile to find where this no doubt carefully constructed fantasy was leading. I bring this up because if you are a fan of fiercely held, but wildly incorrect, physics theories, plus cryptic and archaic language, some of Tesla's crazier ideas, especially his personal concept of "The True Wireless", are most interesting.

Historic  Background

The invention of the telegraph and the telephone were major advances, but both had an important limitation -- you needed a physical connection between the transmitter and receiver. And soon there were efforts to eliminate these annoying wires. Although today "wireless" almost always means "radio" -- even modern "wireless telephones" transmit and receive using extremely high frequency radio signals -- in the late 1800s "wireless" still referred to a number of competing technologies, and thus did not always mean radio waves. You could write a book about the various pre-radio "wireless" communication technologies, and in 1899 J. J. Fahie did just that -- A History of Wireless Telegraphy (1901 edition), which covers numerous approaches developed for wireless signaling, none of which, prior to Marconi's successful demonstration of signalling using radio, had proved commercially practical for long distance communication, although some came close.

Radio, formally defined, is the transmission and reception of electromagnetic radiation -- also known as "radio waves" -- for signalling or other forms of transmitted information. Two of the most celebrated scientific achievements of the 1800s were Clerk Maxwell's mathematical prediction, and Heinrich Hertz's subsequent experimental proof, of the existence of electromagnetic radiation (i.e. radio signals). These two scientific giants showed that a high-frequency alternating electrical current, when sent through an electrical conductor such as a wire antenna, produces electromagnetic radiation, identical to visible light, but with much lower frequencies. A key characteristic of all electromagnetic radiation is that it travels through space as a "transverse wave", usually represented mathematically as the repeating up-and-down tracings of a sine-wave.

Hertz's groundbreaking experiments are best known for showing that radio waves could travel through the air. (Although at the time most scientists still believed in the existence of "the ether", so sometimes they were called "ether waves"). Less well known is that Hertz also showed that, unlike light, radio waves also could travel along the surface of an electrical conductor, such as a wire -- one of his publications was a March, 1889 paper, "On the Propagation of Electric Waves along Wires". In other words, this means that an electrical conductor can act as a "wave guide" for radio signals. It was later discovered, initially by Marconi, that the ground, and especially sea water, also act as waveguides for longwave and mediumwave radio signals, and these "ground waves" (also known as "surface waves", or, in the early days, as "gliding waves") made distant signalling possible, initially to the far side of hills, and later over-the-horizon.

Nikola Tesla always dreamed big. It wasn't just telegraph and telephone wires that offended him, but also electrical power lines, especially the ones running between power stations and consumers. Another thing that made him unique was that, at least through 1919, he didn't believe that the radio signals predicted by Maxwell and experimentally shown by Hertz really existed. He was insistent that no form of unguided "free radiation" could be successfully used for distant communication, instead, what he later called "the true wireless" involved "transmission of electrical energy through the natural medium".

Interesting Trivia: Often overlooked is that Tesla's unworkable idea to use ground currents was merely a variation on earlier unsuccessful attempts to do the same. For example, in 1882, Amos Dolbear applied for U.S. Patent No. 350,299, "Mode of Electric Communication", for "establishing electric communication between two or more places without the use of a wire or other like conductor". He reported successful wireless transmissions of sound for about one-half mile (0.8 kilometers), but was unable to achieve greater distances. And in 1885, Thomas Edison applied for U.S. Patent No. 465,971, "Means For Transmitting Signals Electrically", which proposed "electric telegraphing or signaling between distant points can be carried on by induction without the use of wires connecting such distant points", but this also proved unworkable, even after a trial using transmitter and receiver wires connected to mile-high balloons.
U.S. Patent 465971
Thomas Edison's 1885 patent application, for distant signalling using induction. A short-range "grasshopper telegraph" version, for communicating with moving trains, was successfully tested, but for more distant communication the system worked better on paper than in practice.

In 1891 through 1893, Tesla gave a series of lectures in the United States, London, and Paris. Prominently featured as part of his presentation was the demonstration of the "wireless" lighting of Geissler tubes over short distances. Geissler tubes were glass bulbs from which most, but not all, of the air had been removed. Beginning in the mid-1800s, it was known that the residual gas would light up when an electrical current passed through the bulbs. Tesla hoped to develop Geissler tubes into a form of wireless filament-less lighting -- the July 9, 1891 New York Times, reviewing Tesla's work, noted that "The use of alternating currents of very high frequency makes it possible to transfer by electrostatic or electromagnetic induction through the glass of a lamp sufficient to do away with the lead-in wires." Tesla was ultimately unsuccessful in creating a commercial product, but that has not stopped some of his more enthusiastic admirers from proclaiming him to be the "inventor of the fluorescent lightbulb". (I'll leave it to someone else to write "Nikola Tesla: The Guy Who DIDN'T Invent Fluorescent Lighting", plus the other things he didn't invent, including lasers and computers. I'll put together a signup sheet.)
Tesla demonstrating wireless lighting over short distances to Parisians in 1892. But in this case "wireless" did not mean "radio waves". According to the description in Scientific American, this illustration portrays his use of ordinary induction (not radio signals) to cause Geissler tubes to glow.

Because Tesla used high-frequency electrical currents in these demonstrations, it is sometimes claimed that he had employed radio signals to illuminate the tubes. But it is clear from his descriptions at the time that he was actually using both conduction through the ground and induction -- two examples of technologies that are "wireless", but not the same as "electromagnetic radiation" or radio.

Interesting Trivia: Some earlier experimenters actually had employed the tubes for detecting radio signals, although the device would remain mostly a curiosity in radio development. The first person to use a Geissler tube to detect radio signals appears to have been E. J. Dragoumis, who reported in Note on the Use of Geissler's Tubes For Detecting Electrical Oscillations in the April 4, 1889 Nature that the previous month, following Oliver Lodge's recommendation, he had successfully repeated Hertz's experiments using a Geissler tube as a detector. This in turn led to Richard Threlfall's January, 1890 suggestion that "These tubes have already been successfully applied in Dr. Lodge's laboratory, and if it be permissible to prophesy wildly, we may see in this observation the germ of a great future development. Signalling, for instance, might be accomplished secretly by means of a sort of electric ray flasher, the signals being invisible to anyone not provided with a properly tuned tube."

A publicity article, carried by a number of newspapers in early 1893, provided an expanded report on Tesla's bold proposal for transmitting electrical currents through the ground to great distances -- "Now, at Niagara, for instance, which is destined to be a marvelous center of electrical force for America, enough force can be secured to supply all the needs of the human race twice over. By shaking the entire earth with the mighty power to be obtained there this earth electricity could be started. With this earth force in vibration the next problem would be to build machines able to catch and respond to the earth motion. There would have to be synchronism between the electrical swinging of the earth and the machine. For example, I hold a glass to my mouth and speak. The glass is shattered. My voice to do this must have the same resonance as the glass. Such I conceive to be the secret of all nature--resonance. Then, setting this machine at any point in the world, the message transmitted through the earth can be received and read at Paris, at Hong-Kong--anywhere. Distance no longer exists. I am convinced that I today can send a message to a ship at sea, and that those on board can understand it. If I cannot, I am willing to lay my head on the guillotine."

Tesla never made good on this boast, despite that, his head remained attached to the rest of his body. Assuming that he had made any real attempt at this time at transmitting messages using high-frequency alternating currents, he would have soon found that the easy part was setting up "oscillators" to produce the currents. The far more difficult tasks were modulating, detecting and converting these high-frequency currents into information -- especially full audio -- which would take years of engineering work to perfect. Nothing in these demonstrations or his patents indicate he had the ability to do this, and years later he would write that at the time he had no specific idea how to design something that would "receive intelligence", noting that -- "A specific form of receiving device was not mentioned, but I had in mind to transform the received currents and thus make their volume and tension suitable for any purpose." (This falls into the "easier said than done" and/or "the devil is in the details" category).

Tesla's other widely-publicized proposal was based on a (wild) idea, first put forward by Mahlon Loomis, that a portion of the atmosphere could be employed as a naturally occurring transmission line. Like Loomis, Tesla was under the mistaken impression that an upper layer of the sky was usable as an electrical conductor to replace terrestrial power lines. The main difference between Loomis and Tesla was the former also thought that the upper atmosphere could be treated like a battery that would provide unlimited amounts of electrical power. Tesla added the idea that, like a Geissler tube, the rarified air in the upper atmosphere would glow, providing outdoor nighttime illumination.

Tesla's U.S. patent 645,576, filed September 2, 1897, described in detail his proposed "System of Transmission of Electrical Energy". The patent describes a Loomis-like proposal to transmit electrical currents through a rarefied layer of the sky. However, while Loomis thought it would be possible to draw down existing atmospheric electricity, Tesla proposed using huge transformers to blast "electrical impulses of sufficiently-high electromotive force to render elevated air strata conducting, causing, thereby current impulses to pass, by conduction, through the air strata". The patent specifies massive voltages, starting at 20 to 50 million volts, in order to propel currents via "natural media" conduction. (The patent primarily refers to transmission though rarefied air, but includes the ground as an alternate transmission path). The described "four-circuit" transformer design reflected an approach used for high voltage electrical distribution over wires, with a "step-up transformer" at the transmitting end producing high voltages for the transmission, and a "step-down transformer" at the receiving end, to reduce the voltages to the levels used by electric appliances such as motors. Tesla's Latest Wonder, in the November 13, 1898 San Francisco Call, provided the public an overview of "Tesla's System of electric power transmission through natural media" which he claimed would make it possible to transmit, through the sky, "electrical energy up to practically any amount and to any distance". There is no evidence, however, that Tesla actually ever tried to implement this aerial transmission proposal, and even less that it could have worked. And again, nothing in this approach involved radio signals, just very high voltage electrical currents.

If the sky couldn't replace wires for electrical transmissions, then maybe the Earth could, so Tesla continued investigating the possibility of sending electrical currents through the ground. However, this was not a promising field, since many experimenters, dating back to Carl August von Steinheil in 1838, had found this impossible to do for any significant distance. In 1899, Tesla repaired to Colorado, in order to conduct experiments on the wide open plains. While there, he claimed to have made an historic observation that he thought guaranteed success. He reported developing exceptionally sensitive devices for sensing electrical currents, and moreover said he had used them to detect the lightning flashes from thunderstorms that were hundreds of kilometers away. In his view, this meant that, by creating his own artificial lightning, it would be possible to transmit electricity through the ground for unlimited distances.

Declaring that the time had finally come to convert his exuberant ideas into practical and profitable application, next came the famous and disastrous Wardencliff installation, on Long Island, New York. An enthusiastic Tesla announced the impending commercial introduction of a "worldwide wireless communications system", employing high-powered ground currents, at a time when competing inventors, developing the legitimate, albeit fledgling, wireless technology of radio, were still struggling to set up reliable point-to-point telegraphic communication. John J. O'Neill's biography includes a sample company promotion, circa 1903, of the revolutionary services that supposedly would be provided:
  1. Interconnection of the existing telegraph exchanges of offices all over the World;
  2. Establishment of a secret and non-interferable government telegraph service;
  3. Interconnection of all the present telephone exchanges or offices all over the Globe;
  4. Universal distribution of general news, by telegraph or telephone, in connection with the Press;
  5. Establishment of a World System of intelligence transmission for exclusive private use;
  6. Interconnection and operation of all stock tickers of the world;
  7. Establishment of a world system of musical distribution, etc.;
  8. Universal registration of time by cheap clocks indicating the time with astronomical precision and requiring no attention whatever;
  9. Facsimile transmission of typed or handwritten characters, letters, checks, etc.;
  10. Establishment of a universal marine service enabling navigators of all ships to steer perfectly without compass, to determine the exact location, hour and speed, to prevent collisions and disasters, etc.;
  11. Inauguration of a system of world printing on land and sea;
  12. Reproduction anywhere in the world of photographic pictures and all kinds of drawings or records.

This was Tesla at his visionary best, moreover, according to him everything would be ready in a few months, not 80 years in the future. Unfortunately for his financial backers, who lost their investments instead of getting their promised 100-fold returns, there is no evidence that Tesla made any significant progress in setting up the needed infrastructure or perfecting this amazing technology, and the Wardencliff installation never became operational for any use whatsoever, much less for the heralded world-spanning applications. A few years later the abandoned, unfinished tower was sold for scrap.
Antenna Systems: Compare and Contrast
Shoreham      Shoreham
Tesla's failed Wardencliff "World System" at Shoreham, New York, circa 1903. The mushroom-shaped tower was just the "tip of the iceberg" -- the most important system components were deep underground. Tesla claimed a deep connection was needed to "grip the earth" in order to transmit electrical currents through the ground. It wasn't radio and this endeavor turned out to be a worthless pit into which was poured J. Pierpont Morgan's money. Note that this design didn't have the full above-ground antenna system needed had Tesla been attempting radio signalling, not surprising given that Tesla claimed that what he called "Hertzian longitudinal space waves" were only capable of limited line-of-sight transmissions.      In contrast, in 1920 the Radio Corporation of America -- successor to American Marconi -- very much believed that radio waves existed, and construction of its Radio Central site -- also located on Long Island, New York -- included the type of massive above-ground antenna system needed to effectively fling longwave signals into the atmosphere for trans-Atlantic transmissions. Moreover, it actually worked like it was supposed to.

Undeterred by the inability to convert his ground and sky conduction ideas into actual working practice, Tesla soldiered on with increasingly expansive proclamations. Physicists and electrical engineers pointed out that if you injected electrical currents into the ground, they would spread out in all directions, quickly becoming too diffuse to be usable. Never one to let cruel reality get in the way, Tesla had a ready answer for this, claiming his system had the magical (by scientific standards) ability to directly seek out its targets -- "A popular error which I have often opportunity to correct is the belief that the energy of such a plant would dissipate in all directions. This is not so. Electricity is displaced by the transmitter in all directions equally through the earth and air, but the energy is expended only where it is collected and used to perform some work. A plant of 10,000 horsepower might be running full blast at Niagara, and one flying machine of 50 horsepower might be in another place. Only 50 horsepower would be furnished by the plant." In addition, he continued to stress that his system did not use radio waves (electromagnetic radiation), which he considered a useless waste product, akin to heat, to be suppressed as much as possible -- "Apart from the transmitting and receiving apparatus the only loss incurred is the energy radiated in the form of Hertzian or electro-magnetic waves which can be reduced to an entirely insignificant quantity." (Tesla and His Wireless Age, Popular Electricity, June, 1911).

Always hungry for publicity, newspaper and magazine articles regularly reviewed Tesla's predictions of extraordinary advances, including wirelessly-powered aŽrocars and weather control -- plus, on the more morbid side, the destruction of whole cities, with their inhabitants consumed by electric flame:
Wireless power can be transmitted with absolutely the same facility to the antipodes as it can to a distance of a few blocks.

Neither will the energy or power decrease in efficiency as the distance of transmission increases, as in the case with electrical energy transmitted by wire.

When my system is complete, a crewless ship may be sent from any port in the world to any other port on the Seven Seas, propelled by wireless energy from a power plant anywhere on the face of the earth, and controlled and maneuvered absolutely and positively by telautomatics.

The time will come, as a result of my discovery when one nation may destroy another in time of war through this wireless force; great tongues of electric flame made to burst from the earth of the enemy's country might destroy not only the people and the cities, but the land itself.

The airship of Tesla's invention will neither be aŽroplane nor dirigible, nor will it have wings or gasbags or propeller blades. All these things, he says, are impossible in the construction of a commercially practicable airship. The aŽroplane he classes as no more than an amusing toy, a vehicle for exhibition by the venturesome sportsman; nor will it be anything more, because in its essential principles it has irremediable flaws that are absolutely fatal to commercial success. Tesla's airship will be proportionately as substantial, as stanch and dependable, and altogether as airworthy as the steamship of today is seaworthy. It will maintain a steady, even keel, and will not be in the least affected by air currents or any sort of weather conditions.
    The size of these ships of the air may be limited only by the area of accommodations provided for the landing. Or they may be made small enough, being so easily and simply handled, that the school girl and boy may ride them to and from school, and in greater safety than walking in the streets. The single or double or triple passenger aŽrocar of Professor Tesla's type will be more popular, too, for individual and independent transit, either for business or pleasure, than was the bicycle in its heyday, or the gasolene automobile at its best. Then the city commuter of the future may go and come between business and residence on his wireless aŽrocar, and he may go many miles father afield, into the uncrowded hills and valleys and sea and lake shore, to make his home.

It is claimed, too, as one of the advantages of wireless electricity, that it will be possible to control the weather in any locality to the extent of either preventing or producing rainfall to meet soil and crop requirements. -- Wireless Power, New-York Tribune Sunday Magazine, March 3, 1912.

Editorial Comment: Tesla Motors -- named after Nikola -- started selling automobiles in 2008. However, contrary to Tesla's aŽrocar specifications, these were vehicles that ran on batteries instead of beamed wireless power, and worse, they couldn't fly. I can't help wondering whether Tesla would be disappointed that something so technically backward was named after him. (For more on the sad state of flying car development, see The Onion's Mean Automakers Dash Nation's Hope for Flying Cars).

Tesla's  "True  Wireless"  Manifesto

Tesla's theatrical demonstrations and promotion of "wireless power" yielded plenty of "freak-show" attention. Meanwhile, in the real world, the development of actual working wireless communication, using radio signals, was making people like Marconi famous. (After the April, 1912 Titanic disaster, the New York Times, writing about Marconi, said the survivors "owed life itself to his knowledge as a scientist and his genius as an inventor".) A jealous and frustrated Tesla, annoyed that his bizarre visionary appeals had been ignored and "even at this very day, the majority of experts are still blind to the possibilities which are within easy attainment", wrote The True Wireless for the May, 1919 issue of The Electrical Experimenter magazine (a Hugo Gernsback publication), to chastise his skeptics and provide a detailed review of his eccentric ideas about "wireless" power and communication.

Go ahead and read it. I'll wait. Done? Okay, confused? I'll do my best to interpret and explain.

A good percentage of this article is complete nonsense -- albeit, because of Tesla's elliptical writing style, difficult to decipher nonsense -- showcasing his confused ideas accumulated over the previous three decades, and, to repeat the quote that would appear in his Proceedings of the Institute of Radio Engineers obituary, the reasons why his "theory of the transmission of radio-frequency energy is at variance with that now accepted". Nota Bene: The fact that the same high-frequency electrical currents Tesla experimented with are now called "radio-frequency" (or "RF") is because it was recognized (by others) that their most valuable use is in creating radio signals. You don't see Tesla using this term, again because he didn't think radio waves even existed, and he stated his high-frequency alternating currents needed a conductor to travel any distance.

Tesla opens with an erroneous analysis of the famous experiments by Heinrich Hertz that had proved the existence of electromagnetic radiation, as predicted by Clerk Maxwell. Tesla claimed that Hertz had made a major mistake about the radiation produced by his equipment, in that he only "apparently gave an experimental proof that they were transversal vibrations". Although not detailed in this article, Tesla had long declared that what was actually being emitted by Hertz's experiments were longitudinal phenomena. In other words, according to Tesla, what was produced by Hertz's apparatus were actually compression "space waves" (similar to sound waves), moreover, they had an extremely limited usefulness for wireless signalling -- "The best that might have been expected was a method of communication similar to the heliographic and subject to the same or even greater limitations." (Heliographs, which signalled using light beams, could only be used for line-of-sight communication.) In truth, Tesla's "longitudinal space waves" were his own personal fallacy, and it was Hertz who was correct all along, for it was radio signals, travelling as transverse waves, that were being produced by his experiments.

Editorial Comment: Tesla's terminology can cause confusion. When other scientists and experimenters referred to "Hertzian Waves", they generally meant the transverse waves of electromagnetic radiation, or what we now call "radio waves". But Tesla's idea of "Hertzian waves" as "longitudinal space waves" (which actually existed only in his imagination) means his definition of "Hertzian waves" (and electromagnetic radiation) was completely different from the rest of the world.

Following this unconvincing attempt to debunk Hertz, Tesla describes his misguided conception of "The True Wireless" -- "The idea presented itself to me that it might be possible, under observance of proper conditions of resonance, to transmit electric energy thru the earth, thus dispensing with all artificial conductors." Tesla had consistently stated that a physical conductor was always required for long distance electrical transmissions, either via a wire, or by employing the "wireless" option of using the earth or a rarefied layer of the atmosphere as a natural conductor. (He himself noted: "This mode of conveying electrical energy to a distance is not 'wireless' in the popular sense, but a transmission through a conductor." -- The Future of the Wireless Art section of Wireless Telegraphy and Telephony Popularly Explained, 1908). It is important to note that Tesla never claims to be the "inventor of radio", since in his view electromagnetic radiation was nearly useless for wireless communication. Instead, it was his belief that Marconi, and everyone who followed, had merely stumbled across a feeble version of his own method of transmitting high-frequency electrical currents through the ground. Thus, Tesla believed that what others were calling radio stations were actually inadvertent, albeit poorly engineered, adaptations of his "ground currents", and if people would just listen to him, properly designed "oscillators" could be used to transmit electrical currents through the ground that were billions of times more powerful.

Reviews of Tesla's "true wireless" ideas generally concentrate on the transmission side, where he excelled in developing high-power devices. He most commonly used high speed alternators, which were rapidly spinning mechanical systems, capable of producing alternating currents with frequencies up to about 20 kilohertz. (Irony Alert: The scientific term used for denoting cycles-per-seconds is "Hertz", evidence that the scientific community was more impressed with his experiments than was Nikola). By wire transmission standards, 20,000 cycles-per-second was an extremely high frequency, however, for radio communication this was actually only the lowest tiny sliver of the available spectrum. Tesla, believing that radio stations were actually employing his system of electrical ground-currents, concentrated on the stations that were using frequencies comparable to those which he had experimented with, declaring -- "It occurs to me here to ask the question--why have the Hertz waves, been reduced from the original frequencies to those I have advocated for my system". But this was only a coincidence. Radio stations using extremely low frequencies had superior groundwave signals (although Tesla didn't believe that groundwaves existed -- more on that later), which meant some of the most prominent stations, providing transoceanic service, operated on these frequencies. However, Tesla was ignoring the fact that even at the time this article appeared there had already been an expansion of radio services operating on higher frequencies. And this trend was accelerating, with the revolutionary expansion into shortwave frequencies and above just a few years away. Today, only an extremely small number of radio stations, offering specialized services -- for example, submarine communication and "atomic clock" time services (notice the transmitter tower configuration looks a lot more like RCA's Radio Central than Tesla's Wardencliff) -- operate on the extremely low frequencies that Tesla "advocated" for his ground-current transmissions. One example is literally a museum piece -- station SAQ at Grimeton, Sweden.

And it is clear that Tesla was almost exclusively concentrating on transmitting electrical energy. His patents are explicitly for electrical currents, with nothing covering modulation methods or the reception of signals or sounds. In the article, the diagrams include symbols labeled "receivers", but in his work these just were the transformer coils used to collect alternating current. Although he mentioned "transmitting intelligence" in passing, he confesses that "A specific form of receiving device was not mentioned, but I had in mind to transform the received currents and thus make their volume and tension suitable for any purpose." The article does mention a vaguely defined phenomenon Tesla calls a "rotating brush", which he claimed was "the most delicate wireless detector known". Tesla had actually been promoting this as The Next Great Thing for nearly three decades, without making any measurable progress, and even after all this time had passed, the best he could now say was that he was still hopeful to find it useful in the future, stating only that -- "I am looking to valuable applications of this device". (For a review of the detectors that actually had been successfully developed during the last thirty years for radio reception, see Radio Detector Development, from the January, 1917 issue of The Electrical Experimenter.)

Bizarrely, even though Tesla himself states that the "rotating brush" phenomenon had not yet been developed for any practical use, this article describes it as somehow being "the forerunner of the Audion". ("Audion" was the name Lee DeForest used for his three-element vacuum-tube). In fact, the invention of the Audion and other vacuum-tube detectors was a very well documented -- and completely separate -- line from the never used "rotating brush". The origins began with the "Edison effect", discovered in 1883 by Thomas Edison, who found that lightbulb filaments emitted weak electrical currents. John Ambrose Fleming later added a "plate" element, which allowed him to "rectify" (convert into direct current) the high-frequency currents produced by radio signals. In 1906 Lee DeForest added a third, intervening, "grid" element, to create the Audion, which, in conjunction with later electrical circuits, would provide a far superior method both for receiving transmissions, and for creating high-frequency electrical currents. (Bulky mechanical alternator-transmitters, like Tesla's "oscillators", would soon would be described as "dinosaurs" and replaced by vacuum-tube designs.) Instead of lumping everything together under the broad term of "vacuum tubes", the British commonly use "thermionic valve" to describe the type of vacuum tubes used in radio, which makes clearer the distinction between the three-element vacuum tubes used for radio, and the very different -- both in form and function -- Geissler tubes and "rotating brush" phenomenon promoted by Tesla.

Interesting Trivia: Two classic texts on the history of radio detectors are Gerald Tyne's encyclopedic Saga of the Vacuum Tube and Vivian J. Phillips' comprehensive Early Radio Wave Detectors. Neither has any references to the "rotating brush", or to Tesla at all, for that matter.

In reviewing the adoption of electrical transformers, even here Tesla overstates his own contributions. It is sometimes claimed that effective radio communication didn't exist until Tesla-style transformers were incorporated to create four-circuit configurations. However, radio communication was already making impressive strides before four-circuit designs were developed. A commonly repeated misstatement about Marconi's two-circuit efforts is "some said it could not transmit across a pond", which has the same credibility as "some said the moon landings were faked". For example, Marconi used a two-circuit configuration when he reported the America's Cup race reports in October, 1899, and the G. Marconi's Method chapter in A History of Wireless Telegraphy notes a number of successful transmissions for more than 20 miles (32 kilometers) with the older "two-circuit" design. Moreover, although four-circuit configurations were more efficient, they were not absolutely required. The Federal Telegraph Company of California was sufficiently intimidated by Marconi's legal department to avoid using a four-circuit configuration. Even with this constraint, in 1912 Federal was able to successfully establish a radiotelegraph link between California and Hawaii, spanning 2,350 miles (3,780 kilometers.) (See Federal Telegraph's 1920 Manual of Radio Telegraphy for Radio Operators for more information about their engineering.)

It was true that adopting a four-circuit transformer configuration for tuning was a significant advance for radio technology in the early 1900s. (Sometimes it is implied that all modern radio communication still uses this configuration, but if you open up your wireless telephone expecting to find tiny little Tesla coils, well, you are in for a disappointment). This helped to improve signal strength and, properly configured, narrow the bandwidth of electrical transmissions. But transformers were just one example of a whole series of improvements -- by far the greatest advance would be vacuum tube transmitters and receivers, and the development of audio transmissions, none of which can be traced to Tesla's work. The overall concept of electrical tuning was nothing new -- examples go back to the days of the telegraph, and the development of the harmonic telegraph. From the days of Hertz's experiments it was obvious that synchronizing transmitters and receivers to the same operating frequency would be a valuable step in maximizing efficiency. However, Tesla wasn't the only person involved in the development of tuning (or "syntony", as it was sometimes called). Also, since Tesla didn't believe in the existence of radio waves -- the 1943 case even noted "Tesla in fact did not use Hertzian waves" -- the courts had to determine how much of Tesla's work with high frequency electrical currents applied to radio technology. With his concentration on power transmission, Tesla appears to have been unaware that unless the transformers were properly engineered, the primary and secondary circuits interact, causing the transmissions to be sent on two separate frequencies, while Stone was careful to specify "loose coupling" in order to limit transmissions to a single frequency. Reviewing the Stone tuning patent in 1943, the Supreme Court commended his "intimate understanding of the mathematical and physical principles underlying radio communication and electrical circuits in general", as Stone fully recognized the need for radio transmitters and receivers that could easily change operating frequencies.

For the next few paragraphs Tesla dons an oversized ignorance jacket, and (in his mind) debunks commonly accepted facts about signal propagation. In 1919, it had been well established -- by the scientists and engineers who knew that radio was a valuable technology for wireless communication -- that signals transmitted by longwave and mediumwave stations travelled using two different mechanisms. First were "surface waves" which followed the terrain of the land (the term "gliding wave" was also in common use at the time). But Tesla was incredulous that anyone could possibly believe that such a thing existed -- "I can hardly think of anything more improbable than this 'gliding wave' theory and the conception of the 'guided wireless' which are contrary to all laws of action and reaction. Why should these disturbances cling to a conductor where they are counteracted by induced currents, when they can propagate in all other directions unimpeded?" However, it turned out that the fact that Tesla "didn't think" something existed did nothing to change reality.

Editorial Comment: Two similar terms -- ground currents and ground waves are sometimes confused. Ground currents are merely standard electricity traveling through the ground -- this is what Tesla proposed to use. Ground waves (also known as surface and gliding waves) are radio signals that use the planet's surface as a waveguide to travel to distant points. Tesla didn't believe that ground waves even existed. He was wrong.

Heaviside reflection
Unlike Tesla, the 1906 edition of Lieutenant-Commander S. S. Robison's Manual of Wireless Telegraphy got it right: "Fig. 18g shows the approximate path of an ether wave started from the earth's surface and reflected from the upper atmosphere. It will be seen that even if the earth's surface did not guide the waves they might be detected at points below the horizon."
Apparently deciding he had not yet embarrassed himself enough, Tesla takes on the second transmission mechanism -- signals reflected by the ionosphere -- or, as it was commonly known at the time, the "Heaviside layer". At the time that this article appeared, it had also been well established that longwave and mediumwave radio signals travelled significantly farther at night than during the day. This was known to be due to an ionized layer, around 60 kilometers above the Earth, which reflected radio signals back to Earth after the sun went down. (The "Heaviside layer" name was due to the fact that Oliver Heaviside was one of the first persons to predict the existence of the ionosphere and its effect on radio transmissions). Tesla, however, remained thoroughly unconvinced -- "Terrestrial phenomena which I have noted conclusively show that there is no Heaviside layer, or if it exists, it is of no effect." Tellingly, Tesla never bothers to try to explain why radio stations had greater nighttime coverage, presumably because it is completely unexplainable by "ground currents". (He had, however, a few years earlier made the odd pronouncement that, based on his "ground currents" orientation, the culprit was water evaporation due to the effect of sunlight).

Moreover, as a visionary, Tesla missed out on a technical revolution that was just a few short years away. In the mid-1920s, it would be discovered that shortwave radio transmissions, using frequencies far higher than what Tesla promoted using, had world spanning capabilities, which in no way could be confused as being the result of "ground currents". Their tremendous range was actually the result of the transmissions being reflected by the very Heaviside layer that Tesla had dismissed as either imaginary or inconsequential. (The ionosphere is composed of layers with differing characteristics. In the case of shortwave transmissions -- and unlike longwave and mediumwave -- in some cases it is even more reflective during the day than at night). So, in this case, Marconi was the true visionary, as he would be a major contributor to the development of shortwave radio transmissions.

Radio engineers had successfully designed equipment that provided wireless communication between ground stations and airplanes, and to the engineers it was obvious that radio signals were being sent directly between the two. But Tesla, clinging to his erroneous concept of "longitudinal space waves" and their uselessness for long-distance communication, claimed this was impossible, and said that communication instead was actually via a more circuitous route, with ground currents spreading out horizontally until they were beneath the airplanes, followed by his old favorite, induction, bridging the vertical gap from the ground to the planes. But Tesla's explanation makes no sense and shows the kind of convoluted "logic" he employed in order to try to deny the existence of radio signals. It is notable that he doesn't even try to explain how transmissions could be exchanged between two airplanes not in sight of each other, using his "ground currents" ideas.

This has been a review of most of the main points of the article. There are additional sections which are beyond my ability to figure out what in the world Tesla was talking about. Anyway, enough is enough. Whatever Tesla thought he was doing, it was highly speculative (i.e. not grounded in reality), mostly wrong-headed, and his "true wireless" fantasies were a wild tangent far removed from actual radio communication development. Which explains why Tesla was only a minor figure in the 1943 Supreme Court case, and in no way was declared by same to be "the inventor of radio".

So, to summarize some of the key points:
"The True Wireless", by Nikola Tesla, May, 1919, The Electrical Experimenter
Tesla's Wild ClaimsMundane Reality
Heinrich Hertz's famous experiments had met with wide acclaim by scientists, accepted as having proved not only that radio signals existed, but that they were a form of transverse radiation. In contrast, Tesla thought that this acceptance had "stifled creative effort in the wireless art and retarded it for twenty-five years" for the "Hertz wave theory of wireless transmission" was "one of the most remarkable and inexplicable aberrations of the scientific mind which has ever been recorded in history". In reality, according to Tesla, the "Hertzian radiation" produced by the experiments was what he called "space waves", which travelled through the air (or sometimes "the ether" -- he wasn't consistent on this point) as compression waves (similar to sound waves); moreover, these "longitudinal space waves" were incapable of traveling more than very short line-of-sight distances. Hertz's proof that alternating electrical currents produce transverse radio waves was correct, and in fact a landmark scientific discovery. Unlike Tesla's mythical "longitudinal space waves", radio signals aren't all limited to "line of sight" transmissions, and in some cases are capable of travelling around the world.
Tesla claimed that it was illogical to even believe that "gliding waves" -- longwave and mediumwave radio signals that used the earth as a waveguide to travel to the far side of hills or over-the-horizon -- could exist, because the mere idea was "contrary to all laws of action and reaction". He was dismissive of a series of historic measurements made by Dr. L. W. Austin in 1909 and 1910 -- reviewed in detail by a Bureau of Standards bulletin, Some Quantitative Experiments in Long Distance Radio Telegraphy.Knowledge that conductors can act as waveguides for radio signals goes back to Hertz's early experiments with wires and were confirmed for land by some of Marconi's earliest experiments. The Federal Communications Commission still uses refined versions of the Austin charts -- Kenneth A. Norton and Arnold Sommerfeld in particular added valuable ground wave research -- to calculate the groundwave coverage of AM (mediumwave) stations. The use of conductors as waveguides for electromagnetic radiation was eventually extended to the development of coaxial cable.
Stated that his "true wireless" system could use the Earth as a electrical conductor to transmit "earth currents", for "transmission thru the earth is in every respect identical to that thru a straight wire", and "the amount of energy which may be transmitted is billions of times greater". Electrical currents actually cannot be transmitted effectively through the ground for long distances, it is very inefficient and dangerous, and in doing so you would risk electrocuting vast numbers of people -- much as Tesla would have been electrocuted had he really been sitting that close to those huge sparks in his double-exposure publicity photos. (During the Colorado Springs experiments, nearby horses reportedly received shocks through their shod feet).
Dismissed the value of the Heaviside layer (ionosphere) in aiding long-distance wireless transmission, claiming that his researches "conclusively show that there is no Heaviside layer, or if it exists, it is of no effect".It was well known at the time this article appeared that longwave and mediumwave radio signals travelled significantly farther at night than during the day, due to the signals bouncing off the Heaviside layer (ionosphere) back down to Earth. (The absence of solar radiation at night changes the structure of the ionosphere, which causes it to become reflective.) The first evidence that this was a factor in transmissions dated back to Marconi's 1902 S. S. Philadelphia tests. There was no way to explain this phenomenon according to Tesla's ground currents ideas, so he doesn't even try to provide an alternative explanation.
"Rotating brush" is somehow simultaneously both the "forerunner of the audion [three-element vacuum tube]" and a completely undeveloped technical phenomenon which shows great promise for the future. The "rotating brush" phenomenon was never developed into anything useful. Moreover, three-element vacuum tubes, which were already coming into extensive use for both radio transmitters and receivers, were completely unrelated to the "rotating brush", and in fact had their origins in developments that predated Tesla's first experience with the phenomenon.
"Wireless" communication really didn't exist until four-circuit transformer designs were utilized. The original two-circuit spark-transmitter radio designs, used by Marconi and others, while less efficient, were sufficient to establish radiotelegraphy as a viable communications technology. The initial stage of most technologies is primitive in comparison with later developments. In the case of radio, four-circuit transformers were just one of a multitude of improvements made over the years.

Irony Alert: Shortly after Tesla wrote "The True Wireless", the Westinghouse Electric and Manufacturing Company, which had built its electrical transmission systems around Tesla's alternating current patents, saw the need to invest in radio communication, i.e. the "fake wireless" in Tesla's view. In 1920, the company bought the International Radio Telegraph Company, in order to obtain numerous important Reginald Fessenden radio patents, and to this it added rights to a number of important patents issued to Edwin Howard Armstrong. In early November, 1920, Westinghouse inaugurated a radio broadcasting service from station KDKA in East Pittsburgh, Pennsylvania. Shortly thereafter, Tesla offered his "wireless" services to Westinghouse, but the company declined the offer, happy with the radio version of wireless communication. In November, 1921, the company invited Tesla to speak over one of its radio stations, but the petulant inventor refused, offended because the Westinghouse was not using his (unworkable) "world-system". Although Westinghouse was not the first to make radio broadcasts, the company did do the most to introduce broadcasting in the United States. Its radio investments were soon parlayed into 40% ownership of the Radio Corporation of America. By mid-1920s, it was a pioneer in shortwave transmissions, sending signals around the world using the same Heaviside layer that just a few years earlier Tesla had declared "is of no effect". In 1995, Westinghouse purchased CBS, and two years later it formally changed its entire corporate name to CBS. It still owns KDKA among many other radio stations,[Note: CBS subsequently sold its radio stations to Entercom in 2017] so that "fake wireless" stuff actually turned out to work pretty well.

Further  Information

Many biographical sources about Tesla are factually challenged -- their timelines and antecdotes make for compelling stories, but, to echo Tesla's words from The True Wireless -- "they have always imprest me like works of fiction". Below is a short list of some well researched information about the early development of radio communication. Unfortunately, most of it is not available online. .

Question: So, that takes care of that, right? The "Tesla invented radio" myth has now been fully debunked, and we shall hear of it no more?

Gut Reaction: Are you joking??? There is an endless supply of so-called proofs of Tesla's alleged stupendous achievements -- Example: Of course he never received signals from Mars, he must have actually detected signals from Jupiter, making Tesla the World's First Radio Astronomer! So, think "Titanic vs. The Iceberg" -- at best, before it sinks into oblivion, this webpage might leave a few scrape marks on the Teslaberg.

A More Dignified Response: As noted earlier, the bland assertion "everybody knows" that "Tesla invented radio" can be intimidating, if you don't know the facts. But, like the guy who claimed that "pi is equal to three", Tesla was hopelessly confused on most matters when it came to his concept of "The True Wireless". However, unlike the single "pi lecture", Tesla made decades of expansive proclamations covering, in varying degrees of understandability, far too many subjects to enumerate. Thus, it is all too tempting for his admirers to take some of these vague pronouncements, often out of context, and piece together a supposedly coherent tale (including conspiracy theories) to "prove" that "Tesla invented radio" or some other marvelous achievement decades before anyone else. Or give him the credit for inspiring advances by others that, in fact, are actually far beyond what Tesla had conceived, or even contradict what he had claimed.

There is often a less-than-subtle attempt to use arbitrary terms and dates to make it appear that Marconi (and everyone else, for that matter) were merely copying Tesla's work. If you discount all radio development that came before the adoption of four-circuit tuning, and decide all four-circuit electrical tuning patents, whether they described a use for communication or not, as somehow being radio, and gloss over the fact that sometimes the "wireless" being referred to is a completely different type of technology, such as induction or conduction through the ground (sometimes to the point of rewriting a quote to substitute the word radio for wireless), and you restrict the review to only patents in the United States, ignoring earlier patents in other countries, then eventually you get enough qualifiers to make it appear that Tesla somehow was radio's inventor. (Example: Often ignored is that fact that Marconi's "Provisional Specification" for a system of radio communication, filed in Britain on June 2, 1896, was prior to the Tesla filings for patents which actually were primarily for power transmission and didn't involve radio communication).

At this point I have no expectation that there is anything substantial to the claims made on Tesla's behalf as the "inventor of radio". So, this webpage is my way to document, for my own self, some of the reasons why it just doesn't make any sense to credit Tesla for radio's invention or even development, and make less intimidating the so-called "proofs" that he did. And maybe give some belated recognition to the unheralded John Stone Stone. But as for convincing some who wants to believe in Tesla's priority, that seems impossible -- there will always be another wild goose chase of a so-called proof consisting of convoluted logic to chase down.

Interesting Trivia: Based on some of his later behavior, Guglielmo Marconi is a difficult person to celebrate as the inventor of radiotelegraphy. He pretty much abandoned his family from his first marriage, and became a capital-f Fascist and firm supporter of Italian dictator Benito Mussolini. (An urban legend has even arisen that Mussolini acted as "best man" at Marconi's second wedding, even though there is no evidence that the high-society ceremonies included a "best man", or that Mussolini was even in attendance.) But most people have their own flaws. So, in closing, here's a few Tesla quotes you probably haven't seen before:
This taste for the sensational has always been one of Tesla's commanding characteristics. He prides himself on it. Others may criticise Tesla for this love of the sensational, but he himself will sit for hours talking about some of his seemingly impossible exploits, while the mention of one of his inventions which, as he says, "the world calls practical", will fail to elicit so much as a wink of the eyelash. As he himself told me, it is doubtful if anyone ever performed so many dramatic, hair-raising experiments as he. He is as proud of them as a boy. The zest with which he tells of how, after showing Sarah Bernhardt his most dare-devil exploits, she hurried away almost in a state of nervous collapse, is equalled only by the off-hand manner in which he mentions currents of 80,000,000 vibrations a second, and his descriptions of sparks and flames in his laboratory experiments which rival, if not equal, the lightning itself. -- Arthur B. Reeve, "Tesla and His Wireless Age", Popular Electricity, June, 1911.

Some animal is now brought out from a cage, it is tied to a platform, an electric current is applied to its body and in a second the animal is dead. The tall young man calls your attention to the fact that the indicator registers only one thousand volts, and the dead animal being removed, he jumps upon the platform himself, and his assistants apply the same current to the dismay of the spectators. -- Chauncey Montgomery M'Govern, "The New Wizard of the West", Pearson's Magazine, May, 1899.

By exposing the head to a powerful [X-ray] radiation, strange effects have been noted. For instance, I find that there is a tendency to sleep, and the time seems to pass away quickly. There is a general soothing effect, and I have felt a sensation of warmth in the upper part of the head. -- Nikola Tesla, "On Roentgen Rays", Electrical Review, March 11, 1896.

Laxity of morals is a terrible evil, which poisons both mind and body, and which is responsible for a general reduction of the human mass in some countries. Many of the present customs and tendencies are productive of similar hurtful results. For example, the society life, modern education and pursuits of women, tending to draw them away from their household duties and make men out of them, must needs detract from the elevating ideal they represent, diminish the artistic creative power, and cause sterility and a general weakening of the race. -- Nikola Tesla, "The Problem of Increasing Human Energy", The Century Magazine, June, 1900.

    You ask me about atomic energy? I experimented with the atom, and achieved similar ends, long before the wave of ballyhoo swept over the country in recent years. The idea of atomic energy is illusionary but it has taken a powerful hold on the mind and there are still some who believe it be be realizable.
    I have disintegrated atoms in my experiments with a high potential vacuum tube I brought out in 1896 which I consider one of my best inventions...
    But as to atomic energy, my experimental observations have shown that the process of disintegration is not accompanied by a liberation of such energy as might be expected from the present theories. -- Modern Mechanix, July, 1934.