TESLA AND THE INVENTION OF RADIO

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TESLAAND THE INVENTION OF RADIO
Borivoje Nikolic Department of Electrical
Engineering and Computer Sciences University of
California, Berkeley bora_at_eecs.berkeley.edu
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History of Radio

• Maxwell electromagnetic theory 1864
• Heinrich Hertz experimentally have proven that
  electromagnetic waves do exist, and propagate
  with a finite velocity

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Maxwells Theory

• Electromagnetic theory in 1864
• Mathematically proved the theory that that any
  electrical disturbance could produce an effect at
  a considerable distance from the point at which
  it occurred and predicted that electromagnetic
  energy could travel outward from a source as
  waves moving at the speed of light.

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Hertzs Experiments

• First radio communications experiments 1885-1889
• Demonstrated in 1888. that Maxwell's predictions
  were true at least over short distances by
  installing a spark gap (two conductors separated
  by a short gap) at the center of a parabolic
  metal mirror. A wire ring connected to another
  spark gap was placed about 1.5 meters away at
  the focus of another parabolic collector in line
  with the first. A spark jumping across the first
  gap caused a smaller spark to jump across the gap
  in the ring five feet away. Hertz showed that the
  waves traveled in straight lines and that they
  could be reflected by a metal sheet just as light
  waves are reflected by a mirror.

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Hertzs Experiments

• Very high frequencies of operation 50-500MHz
• Demonstrated wave properties - reflection,
  refraction and polarization
• But, spark gap detectors are quite impractical
  for wide use
• Sparks, spectrum, power

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Coherer

• Need a better detector for electromagnetic
  (radio) waves
• Around 1890 there was no electronics, amplifiers,
  semiconductors (as we use them today)
• Electron was discovered 1897 (J.J. Thompson).

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Coherer

• Edouard Branly, 1890.
• Improved by Sir Oliver Lodge

Relay or tape
Coherer Glass enclosurefilled with metal powder

• Perfected by Guglielmo Marconi

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Guglielmo Marconi

• Wireless experiments 1894-1896.
• Perfected the coherer 2mm device
• Covered Americas Cup yacht race minute-by-minute
  for the newspapers in 1899.
• In 1901. he achieved the transmission of
  telegraph signals from England to Newfoundland,
  using a crystal detector.

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Crystal Detectors

• J. C. Bose in 1899. reported a point contact
  detector based on galena(lead sulfide), a
  semiconductor crystal
• Phenomenon of asymmetrical conduction already
  reported by Ferdinand Braun in 1874

First electrode
Second electrode
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Crystal Radio
Crystal radio
LC tank
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Crystal Detectors

• These detectors were used by Marconi to achieve
  transatlantic wireless signal transmission
• He used a mercury-based detector, connected to a
  kite 400ft in the air (antenna) in series with
  phone earpiece, and other end grounded.

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Crystal Detectors

• He claimed that he got the detector from his
  friend Lieutenant Solari from Italian Navy
• Filed for patent in 1901.
• In fact, it was the same detector as Boses

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Commercial Radio

• Marconi covered Americas Cup yacht race for New
  York Herald and Evening Telegram in 1899 by
  wireless telegraphy.
• It was a huge success in 1901, two more groups
  (besides Marconi) tried to cover the race but
  there was no success. Leader of one of the
  groups, Lee de Forest threw his transmitter
  overboard.
• Marconi started Marconi Wireless Telegraph
  Company

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Popovs Radio Experiments

• Around 1895 (?) wireless transmission over 600m
  distance
• In 1897 Russian navy cruiser Africa was equipped
  with wireless communication system with base in
  Kronstadt

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Tuned Circuits

• Tuned circuits are added to filter out the
  interference.
• Was thought to be the key for the development of
  wireless telegraphy
• Attributed to Marconi, patent filed in 1900.

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Teslas Tuned Circuits

• But the same idea was already patented and used
  by Tesla!

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What was Tesla interested in?

• In wireless transmission of energy and information

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The Magnifying Transmitter

• World Wireless System
• Built on Long Island
• 1901-1903
• Funded by J.P. Morgan
• Demolished in 1917.

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World System

• 1.The interconnection of existing telegraph
  exchanges or offices all over the world
• 2.The establishment of a secret and
  non-interferable government telegraph service
• 3.The interconnection of all present telephone
  exchanges or offices around the Globe
• 4.The universal distribution of general news by
  telegraph or telephone, in conjunction with the
  Press
• 5.The establishment of such a "World System" of
  intelligence transmission for exclusive private
  use
• 6.The interconnection and operation of all stock
  tickers of the world
• 7.The establishment of a World systemof musical
  distribution, etc.

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World System

• 8.The universal registration of time by cheap
  clocks indicating the hour with astronomical
  precision and requiring no attention whatever
• 9.The world transmission of typed or handwritten
  characters, letters, checks, etc.
• 10.The establishment of a universal marine
  service enabling the navigators of all ships to
  steer perfectly without compass, to determine the
  exact location, hour and speak to prevent
  collisions and disasters, etc.
• 11.The inauguration of a system of world printing
  on land and sea
• 12.The world reproduction of photographic
  pictures and all kinds of drawings or records..."

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From My Inventions

• My project was retarded by laws of nature. The
  world was not prepared for it. It was too far
  ahead of time. But the same laws will prevail in
  the end and make it a triumphal success.

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Teslas Patents on Radio

• Sept. 2, 1897 System of Transmission of
  Electrical Energy 645,576
• Sept. 2, 1897 Apparatus for Transmission of
  Electrical Energy 649,621
• July 1, 1898 Method of and Apparatus for
  Controlling Mechanism of Moving Vessels or
  Vehicles 613,809
• June 24, 1899 Apparatus for Utilizing Effects
  Transmitted from a Distance to a Receiving Device
  Through Natural Media 685,955
• June 24, 1899 Method of Intensifying and
  Utilizing Effects Transmitted Through Natural
  Media 685,953
• Aug. 1, 1899 Method of Utilizing Effects
  Transmitted Through Natural Media 685,954
• Aug. 1, 1899 Apparatus for Utilizing Effects
  Transmitted Through Natural Media 685,956
• May 16, 1900 Art of Transmitting Electrical
  Energy Through the Natural Mediums 787,412
• July 16, 1900 Method of Signaling 723,188
• July 16, 1900 System of Signaling 725,605
• Jan. 18, 1902 Apparatus for Transmitting
  Electrical Energy 1,119,732

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Wireless Automation

• Tesla also worked on Telecontrol.
• Work started around 1893.
• Demonstrated a remotely controlled submarine in
  1898.

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Nobel Prize

• 1909 Nobel prize in Physics was awarded jointly
  to GUGLIELMO MARCONI and CARL FERDINAND BRAUN
  in recognition of their contributions to the
  development of wireless telegraphy.

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Law Suit

• Marconi Wireless Telegraph Company of America vs.
  United States.
• Four patents (owned by Marconi)
• Two-circuit tuning, by Marconi, 1901.
• Four circuit tuning, by Marconi, 1904. (claimed
  to be the key)
• Use of variable inductance for tuning (Lodge,
  1898)
• Rectifier tube (Fleming, 1905)

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Court ruling

• After many years of dispute, in on June 21, 1943,
  the U.S. Supreme court ruled to invalidate
  Marconis four circuit patent No. 763, 772 in
  favor of Teslas No. 645,576.

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Teslas Honors

• The IEEE, which considers Tesla one of the 12
  "apostles" of electrical science, continues to
  offer an annual prize in the field of power
  engineering in his name. And in 1960, the "tesla"
  was named the international electrical unit of
  magnetic flux density.

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History of Radio (continued)

• Spark transmission was replaced by sine wave
  (narrow band) produced by oscillators
• AM Radio broadcast in 1906.
• 1907 Lee de Forest invented the triode vacuum
  tube - audion (similar device was patented before
  by Edison in 1884)
• Armstrong stated using it around 1914.
• Invented superheterodyne receiver in 1917.

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Todays Radios
Cellular phone
Coherer
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Future Radios