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Microwave
Hall of Fame
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Long before any study of microwaves occurred, Scotsman John
Napier, born in 1550, developed the theory of logarithms,
in order to eliminate the frustration of hand calculations
of division, multiplication, squares, etc. We use logarithms
every day in microwaves when we refer to the decibel. His
"numbering rods", constructed of ivory, became known
as "Napier's Bones", and comprised the world's first
slide rule. Some of his neighbors suggested that he was in
league with the powers of darkness... a trait that has often
been associated with successful microwave engineering! The
Neper, a unitless quantity for dealing
with ratios, is named after John Napier. |
Microwave antennas often use a Cassegrain reflector. Not much
is known about Laurent
Cassegrain, a Catholic Priest in Chartre, France, who
in 1672 reportedly submitted a manuscript on a new type of
reflecting telescope that bears his name. The key features
are a secondary convex mirror suspended above the primary
concave mirror, that focusses light into the eyepiece which
is located in a hole in the primary mirror. The Cassegrain
antenna is an an adaptation of the telescope. |
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Lazzaro Spallanzani, born in 1727 in Italy, had a huge
influence on many of the physical sciences, which is even
more remarkable because he was an ordained Jesuit priest.
Here in the Microwave Hall of fame, Spallanzani is remembered
because his Lettere sul volo dei pipistrelli acciecati,
published in 1794, recorded correspondence about his experiments
on the remarkable sense of direction of bats. Bats use sonar
to move about in the dark, which some might argue was the
inspiration for radar. |
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Hans Christian Oersted was born in 1777 in Denmark, and was a lifelong academic specializing in the physical sciences, as well as an amateur philosopher, a follower of Kant. Oersted's discovery in 1820 that an electric current would deflect a compass needle was the first proof that electricity and magnetism are like beautiful twin sisters Mary-Kate and Ashley Olson, irresistible to engineers, and always touching each other! The unit of magnetic field strength was named the Oersted in his honor. One of Denmark's greatest thinkers, Oersted founded the Polytechnical Institute in Copenhagen in 1829, which is now known as the Technical University of Denmark.
Also born in 1777 was Johann Carl Friedrich Gauss. Born in Braunschweig, Germany, Gauss is regarded by many as the most prominent mathematicianever. His numbers work is too numerous to even be listed here and much of it seems esoteric to engineers, such as his solution to circumscribing a 17-sided polygon inside a circle. (This is what he wanted on his grave stone)! He also proved that any integer can be expressed as the sum of no more that three triangular numbers, not something that you might use ever day. His name is used every day in discussions of probability theory (Gaussian distribution). He also was a major contributor to physical sciences, inventing the heliotrope (for measuring long distances using sunlight) and developed accurate methods for measuring terrestrial magnetism. He helped install a telegraph system in Europe, at the same time accomplished painter Samuel Morse was working on his system in the United States. Let's not forget Maxwell's equations includes two that are derived from Gauss (magnetic and electric induction). The CGS unit of electromagnetic induction is the "Gauss", in his honor. Gauss died in 1855.
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Christian Andreas Doppler
was born in Austria in 1803. Being too much of a pencil-neck
for the family stonemason business, he learned mathematics at
the Vienna Polytechnic Institute. His theory of the apparent
shift in frequency when source or observer was in motion relative
to the other was proved using musicians on trains and train
platforms listening for what notes the others were playing.
He correctly predicted that the concept would prove valuable
in astronomy in determining celestial motion because of color
shifts. Doppler radar is used everyday, by pesky police radars
for one trivial example. He died young at age 49. |
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At the same time Faraday was working on EM theory, Princeton
Professor Joseph
Henry was also playing with large electromagnets, developing
one that lifted 750 lbs., partly because he was the first person
to consider source and load
impedance matching to maximize power
transfer. In his own words, one of Henry's experiments "illustrates
most strikingly the reciprocal action of the two principles
of electricity and magnetism". He was also the first curator
or the Smithsonian Institute, and his work on self-induction
is remembered today because the unit of inductance is the Henry.
Henry lived a full life, from 1797 to 1878. |
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In 1873, country-boy misfit James
Clerk Maxwell laid the foundations of modern electromagnetic
theory in his work, "A Treatise on Electricity and Magnetism"
in Scotland, which he wrote as a retired college professor.
Born in 1831, and nicknamed "Dafty" by his childhood
peers, Maxwell theorized that, if combined, electrical and magnetic
energy would be able to travel through space in a wave. If Maxwell
were here today, he would be pleased to see
his equations routinely solved many thousands of times per
second by today's three-dimensional structural simulators using
finite element analysis. Dr. James C. Rautio, founder of Sonnet
Software, Inc. (one of our sponsors!), seems to have made the
study of Maxwell a personal quest. He's a Distinguished Lecturer
of the IEEE for 2005, and his talk entitled The Life of James
Clerk Maxwell, is not to be missed, animated with at times
with different voice impressions of 19th century Scotsmen (div
ye ken?) You can download a copy of an excellent public-domain
biography of Maxwell, written in 1882 by his friend Lewis Campbell,
thanks to James Rautio, who personally scanned it into a pdf.
Its tucked up under "products" on the
Sonnet web site. For those of you that don't read much,
it has some great contemporary pictures! |
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"the method of, and apparatus for, transmitting vocal or other sounds telegraphically… by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound." Three weeks later Alexander Graham Bell's famous sentence, "Watson, I want to see you", was spoken into the first telephone. The same month, Custer's army became human pincushions. Bell was born a Scot in 1847 and came to the "New World" by way of Canada, later settling in Boston. His portfolio of inventions is second to none, but his life's work was mainly centered on helping the deaf. The term bel (and decibel) was named by Bell Labs scientists to honor him. Bell thought the phone was too great a distraction, and refused to permit one in his study! Bell died in 1922. |
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By the 1880s, electrification of the world had begun, first for lighting, and just as important, for motors. In the United States, a huge rift developed between supporters of direct current systems (being deployed by Edison), and supporters of alternating current (to be deployed by Westinghouse). Eventually, Nikola Tesla proved to the world that alternating current and his polyphase system of generation, distribution and power delivery using the induction motor were the answer to long distance, reliable electrical distribution. New York City was wired with direct current for a time, and unreliable DC trolleys and their sparking commutators gave the Brooklyn Trolley Dodgers baseball team (today's L. A. Dodgers) their name. During this time period, "Wizard of Menlo Park" Thomas Edison performed despicable acts on neighborhood pets to show the dangers of alternating current, and eventually arranged for the first prisoner execution on August 6, 1890, using (of course) alternating current. Convicted killer William Kemmler took eight minutes to die, even though the procedure had been tested on a horse the day before. To see the botched execution from the movie Green Mile, click here (fair warning, this is a truly ugly event). The late 1800s/early 1900s were certainly the most interesting of modern times for technology. You can read about this time period in books such as Tesla, Man out of Time, by Margaret Cheney.
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Charles Proteus Steinmetz in his cabin near Schenectady. Looks like the museum incorrectly painted the replica table white! Steinmetz was a socialist, which is what brought him to the United States (he had to flee Germany after writing political essays). He was also an environmentalist, an anti-racist, a protagonist of electric cars to reduce pollution, and a big fan of cigars. He preferred to live in a camp near General Electric's Schenectady plant, using a canoe as his fair-weather office. He had 200 US patents. |
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Edison might be spinning in his grave these days, as high-voltage DC transmission line haves made a comeback of sorts. Once the problem of up/down converting is solved (which is an expensive proposition), DC has two advantages over AC: lower peak voltage for the same power (less opportunities to arc), and the skin depth at DC is infinite. Every gram of copper in a DC transmission line is used to move power equally, this is not true for AC. Therefor DC has a loss advantage which can be appreciable for large diameter lines. Here's some info on HVDC power transmission lines.
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In another experiment, Hertz used a coax line to show that electromagnetic waves propagated with a finite velocity, and he discovered basic transmission line effects such as the existence of nodes in a standing wave pattern a quarter wavelength from an open circuit and a half wavelength from a short circuit. He then went on to develop cylindrical parabolic reflectors for directional antennas, as well as a number of other radio frequency (RF) and microwave devices and techniques.
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Others soon built on Hertz's work. In 1894, 20 year old Guglielmo
Marconi began experiments in Italy sending a wireless signal
using Morse code, at first for short distances, and ultimately
thousands of miles. Marconi was the son of a wealthy Italian
businessman and an Irish mother who was part of the Jameson
family whose distilled products were (and are) well known. He
had limited education and no formal training as engineer or
scientist, just an idea that wireless communications would one
day render the telegraph obsolete, and the wherewithal and family
support to pursue his dream. Marconi brought together the "perfect
storm" of engineering curiosity (notice we didn't say "scientific"),
confidence, financing and ego that comes along once in a lifetime
to rattle the establishment out of bed and change the world.
His only equal today would be be Bill Gates. |
Marconi faced resistance, resentment and reprisals from many well-known scientists of the era, and almost lost his personal fortune. His high-tech startup of the '90s, The Wireless Telegraph & Signal Company (a U.K. company) was soon renamed Marconi's Wireless Telegraph Company. This business began by installing company-owned and operated wireless communications onto ships to communicate with huge installations on key coastlines, while the founder pursued ground communications across the Atlantic. It is ironic that Marconi's methods of trial and error for tuning his equipment would have taken much longer if not for access to transatlantic cables owned by the telegraph companies his technology would compete with. Marconi received the Nobel physics prize of 1909 for his work, shared with German Ferdinand Braun. By 1911, "Marconigrams" had helped capture a famous murderer and in 1912 enabled the rescue of Titanic survivors. Marconi was the first experimenter to notice that transmission during daylight hours was more prone to noise than at night, which was later explained by Heaviside as due to the "Marconisphere" (now known as the ionosphere). Approximately 350 civilian Marconi wireless operators were killed at sea during the first World War, as the wireless shed was a crucial target for maritime marauders. Although Marconi was the singular force behind long distance wireless communications, he admitted he didn't really know how it all worked. Some years later the scientific community discovered that Marconi's idea that longer wavelengths would travel farther around the globe was incorrect, and Marconi's amazing 300,000 watt steam-powered spark gap transmitters, building-sized capacitor banks and multi-mile antenna elements were unnecessary at higher frequencies (short waves). Marconi died in 1937, to learn more about his life and that of murderer Harvey Crippen, go to our book page and order Thunderstruck. Marconi's company has long since has been chopped up and digested into BAE and Ericsson among others.
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As the son of a minister, Fleming got his shorts in a knot about Darwin's theory of evolution. |
Father Landell de Moura is a little known pioneer of wireless
transmission of voice. In 1900 he publicly demonstrated voice
transmission while others were merely transmitting Morse code.
In 1901 he received a patent in Brazil for "equipment for
the purpose of phonetic transmissions through space, land and
water elements at a distance with or without the use of wires".
He then traveled to the United States where he was awarded three
patents in 1904: the "Wave Transmitter" which is the
precursor of today's radio transceiver, the "Wireless Telephone"
and the "Wireless Telegraph". His sketches have survived,
and his equipment has been duplicated in modern times to show
he was on the right track. Read his fascinating
Wave Transmitter patent here. Nominated by Ricardo, an Electrical
Engineering student at University
of Campinas, Brazil, and fan of microwaves101.com! |
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Brian wishes to point out that Fessenden, Tesla, Charles Steinmetz and Ernst Alexanderson all worked for Edison. Is the top genius the one who can make business out of the genius of others? How many similar genius’s worked for Bill Gates and helped him make his billions and whom we will only hear about 100 years from now if ever? |
Michelson was the first US scientist to win the Nobel prize for Physics, in 1907 "for his optical precision instruments and the spectroscopic and metrological investigations carried out with their aid". Later he continued to improve measurement accuracy of the velocity of light, and his most accurate experiments occurred after he was 70 years old. By 1926 he had data to show 299,796±4 km/s, from a measurement between Mt. Wilson and Mt. San Antonio in California in today's Angeles National Forest. To get this accuracy, distance needs to be accurate to centimeters across the 35 km separation. In 1929 he set about to measure speed of light in vacuum in a one mile pipe. He died in the middle of the experiment, which turned out to be corrupted ±10 km/s by the slipping San Andreas fault, alluvial soil and sea tides. Without an accurate value for "c", radar would be in serious trouble. Learn more about speed of light measurement here. If you have the opportunity to visit the Naval Air Weapons Station at China Lake, you might visit "Mich" labs, named after Michelson, which has a great exhibit of Michelson artifacts in the lobby. Be sure to pronounce it "Mike Lab"! |
The Michelson-Morley experiment is regarded as the greatest failed experiment of all time. Using the amazing interferometer they developed together (think pool of mercury floating a one-foot thick slab of granite) in 1887 at what is now Case Western Reserve University, M&M set out to measure how the "aether wind" affects the speed of light. This hypothesis proved wrong, aether wind was not detected, and the second scientific revolution had begun. Read Michelson and Morley's 1887 American Journal of Science paper here! Michelson was the first person to measure the diameter of a star (Betelgeuse) in 1927. |
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Textronix named a street "Karl Braun Drive" at their Beaverton facility. They also named streets after Schottky, Terman, Shannon, Zworykin and more electronics' pioneers. Check it out! |
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Lee de Forrest (1873-1961)
was a prolific inventor (180 patents) and is regarded as inventor
of the three-terminal tube, which he called the audion. Many
regard him as the father of radio. By adding the grid to Fleming's
diode "valve", de Forest showed how to control the
signal but did not achieve amplification with the three terminal audion, which in hindsight is arguably one of the top ten inventions in the history of the world. Later
inventors, most notably Armstrong, built on de Forest's discoveries
and radio soon became a rage; even non-electronics companies
such as Radio
Flyer cashed in on the name. De Forest disliked the word
"wireless", and helped populate the new word "radio"
which was derived from radiation. Many early radio inventors
were pawns of giant industrial companies such as Westinghouse,
AT&T and General Electric, and the fight over patent rights
was fierce and discredited some of the best minds in the field.
De Forest suffered as much as any, in the patent fight of the century for who invented the regenerative receiver. Even then almost all radio engineers accepted that Armstrong was the inventor, but patent law can be a tangled web indeed. De Forest went through four marriages,
but lived a long life and saw radio move from curiosity, to
invaluable war and peacetime communication tool, to mass media
outlet. Lee spent many good years in Hollywood, among other
honors won
an Oscar for developing a way to add sound to motion pictures.
Late in life he became disillusioned with radio, as he was neither
a fan of pop music nor advertising. Neither was Elvis Costello back in 1977... Nominated by Brian! |
 Lee de Forest |
William Henry Bragg
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In microwave engineering, semiconductors are analyzed using crystallography. We have also adopted a dual meaning: Bragg frequency refers to the frequency where a periodic structure suffers from additive interference and hence ceases to function. Examples of Bragg frequency can be found in studies of slow wave lines and artificial transmission lines. |
William Lawrence Bragg
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Mad scientist Oliver
Heaviside's research in transmission-line theory was first
applied to telegraphs, including the transatlantic cable, but
microwave engineers use his concepts to this day. A mathematician,
he rewrote Maxwell's messy equations into their simple, vector-calculus
form. He predicted the E-layer of the ionosphere, which allows
propagation of electromagnetic waves around the curvature of
the earth. A trendsetter years ahead of Ed
Wood, he painted his nails pink! |
Leo
Hendrik Baekeland was born in Ghent, Belgium on November
14, 1863 to poor parents, yet earned his doctorate at University
of Ghent by the age of 21. He emigrated to the U.S in 1889,
and made his original fortune selling a process for photographic
paper to George Eastman for $1,000,00 in the 1890s. Later experimentation
by Baekeland resulted in discovery of the very first plastic,
a thermoset compound created from formaldehyde and phenol that
became known as Bakelite.
Bakelite was a huge enabler for bringing radio to the masses,
not just as a substrate for mounting electrical components due
to its insulating property, but also as the material for mass
producing cabinets.
Click this link to go to the radio museum and notice the
progression from hand crafted wood cabinet to molded enclosure
during the 1930s. There's at least one Bakelite
museum! Baekeland died in 1944, we can't help but wonder
what his coffin was made of! |
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Watch David Bowie play Tesla in the movie The Prestige! |
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By 1894, Sir Oliver George was conducting experiments noting that
directional radiation was obtained when he surrounded a spark oscillator
with a metal tube. In 1897, Lord
Rayleigh (John William Strutt) proved mathematically that waves
could be propagated inside a hollow metal tube. Rayleigh also noted
the infinite set of modes of the TE or TM type which were possible,
and the existence of a cutoff frequency. Waveguide was essentially
forgotten, however, until it was rediscovered independently in 1936
by George C. Southworth at AT&T (Bell Telephone Labs) and W.L.
Barrow at MIT.
Up until this point, focus had been on sending and receiving communication signals. As the new century progressed, scientists worked with longer and longer wavelengths to achieve greater and greater distances.
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In 1911, only three years after building
the first helium liquefier, Heike
Kamerlingh-Onnes discovered that mercury loses its electrical
resistance entirely when cooled below 4.2 K in a liquid helium
bath. Why do we include the discoverer or superconductivity
in the microwave hall of fame? Stick around, the best in microwaves
is yet to come with the advent of high-temperature
superconductors! |
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As radio applications grew more sophisticated (and popular), stations started broadcasting regular commercial programs. By 1920, the US Department of Commerce stepped in and began issuing radio licenses, and in 1921 formally declared a special service category (and corresponding transmission wavelength) for commercial stations.
Want more? Check out the next room in the Microwave Hall of Fame!
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