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Philip H. Smith: A Brief Biography
by Randy Rhea, Noble Publishing
Phillip Hagar Smith was born in Lexington, Massachusetts on April 29, 1905,
to George and Rose Whitney Smith of Scotch and English ancestry. Rose Whitney
was a descendant of Eli Whitney, the inventor of the cotton gin. While
attending Tufts College, Phil was an active amateur radio operator with the call
sign 1ANB. He also played the cornet in the Tufts College band. To commute
between Lexington and Tufts, he drove a reconstructed model T Ford and later a four
cylinder Harley Davidson motorcycle. He received the BSEE degree from Tufts
College (now Tufts University) in 1928, majoring in electrical communications.
In 1928, he joined the technical staff of Bell Telephone Laboratories with
the Radio Research Department in Deal, NJ where he worked under J.C. Schelleng and
E.J. Sterba. In these early days, Phil became involved in the design and
installation of directional antenna equipment for commercial AM radio
broadcasting. In 1929 he was working in Lawrenceville, New Jersey, on an antenna system
which was designed to communicate by shortwave with Europe and South America.
The antenna was connected to the transmitter by a two wire transmission line.
Perhaps the major reference at the time was J.A. Fleming's 1911 telephone
equation, which expressed the impedance characteristics of high frequency
transmission lines in terms of measurable effects of electromagnetic waves
propagating thereon, i.e, the standing wave amplitude and the wave position.
In the reprint of an article entitled "Transmission Lines for
Short-wave Radio Systems," presented at the IRE 20th anniversary convention
in April 1932, there was a footnote which read "Disclosed to the writers by
P. H. Smith, Bell Telephone Laboratories." The footnote referred to a
paragraph in the article which began, "There is another effective way for
transforming line impedance by means of short line devices...." It was the
first published report of Phil's work, work that ultimately led to the
creation of the Smith Chart.
In spite of his long identification and association with antenna activities,
Phil was basically a transmission line engineer. He relished the problem of
matching the transmission line to the antenna, a component which he considered
matched the line to space. Considering the frequency and the consequent large
size and resultant cumbersomeness of the antenna, the measurements were not
simple. In those early days, the sensing element was a thermocouple bridge with
about 6 or 8 thermocouples coupled to two coils, whose dimensions were
determined by the frequency of transmission. The indicator was a microvoltmeter
which measured the magnitude of the signal. The entire assembly was then moved
along the transmission line to determine the relative magnitude and location of
the maximum and minimum signals. For transmission lines high in the air, this
required one individual to move the sensing device along at the end of a long
pole, while a second individual would read the signal through a telescope. It
was primitive, but it worked. This was the early environment that Phil faced as
an electrical engineer with the Bell Telephone Laboratories. For those who knew
him best, it was no surprise that he would doggedly pursue his goal of creating
a chart to simplify the work. From Fleming's equation, and in an effort to
simplify the solution of the transmission line problem, he developed his first
graphical solution in the form of a rectangular plot.
Phil persisted in his work, and the diagram gradually evolved through a series
of steps. The first rectangular chart was limited by the range of data it could
accommodate. He was aware of the limitations and kept working on the problem
until some time in 1936, when he developed a new diagram that eliminated most of
the difficulties. The new chart was a special polar coordinate form in which
all values of impedance components could be accommodated. The data for this
diagram was scaled from the earlier rectangular diagram. The impedance
coordinates in this case were not orthogonal and were not true circles, but, in
the form chosen, the standing wave ratio was linear. The chart closely
resembled what ultimately became the final result.
Phil, however, suspected that a grid made up of a system of orthogonal
circles might be more practical. He felt it would have distinct advantages,
particularly as regards reproducibility. With this in mind, he spoke to two of
his co-workers, E.B. Ferrell and J.W. McRae. Because they were familiar with
the principles of conformal mapping, they were able to develop the
transformation whereby all data from zero to infinity could be accommodated.
Fortunately, curves of constant standing wave ratio, constant attenuation and
constant reflection coefficient were all circles coaxial with the center of the
diagram. The scales for these values, while not linear, were entirely
satisfactory. A diagram designed along these lines was constructed in early
1937. It was essentially the form still being used today.
Smith approached a number of technical magazines with regard to publication
of the Chart, but acceptance was slow. There were not many technical magazines
at the time, and none in the microwave area. However, in January of 1939, after
a delay of two years, the article was printed in Electronics magazine.
A fact one cannot ignore is that many highly competent people proposed
charts for use in solving transmission line problems. Some of their charts had
brief periods of popularity, but it is a comment on Phil's persistence in
searching out the ultimate solution, that his Chart stands out above all others
in its use and usefulness.
It took a while for Phil to convince other people of the utility of his
chart. One of the first individuals to see its value was A.G. Fox at Bell Labs,
who in 1939 found it useful in some early work he was doing on the new subject
of waveguides. When the M.I.T. Radiation Laboratory was formed in 1940, the
value of the Smith Chart was recognized immediately and it was put into general
use. According to Phil, the M.I.T. workers were his first customers. It would
be hard to visualize many of the achievements of the M.I.T. Rad Lab without some
help from the Smith Chart. For microwave people at that period, the Smith Chart
had the equivalent impact of turning on a bright light in a previously dark
Phil published a second article in 1944 which incorporated further
improvements including the use of the chart with either impedance or admittance
coordinates. In 1958, in the first issue of the Microwave Journal, a biography
of Phil was published to acknowledge the importance of his contribution. In a
series of six subsequent issues of the magazine, Dr. George Southworth described
the importance and some of the applications of the Smith Chart.
According to Dr. Southworth, the Smith Chart, even in its earliest form, was
no sudden flash of genius. Phil's first ideas were imperfect and they required
time for full maturity. However, as Dr. Southworth wrote, "it was to his
everlasting credit that he did not allow his idea to die on the vine, but
nourished it until he had brought it to a high degree of perfection."
Today's emergence of the digital computer as a dominant design tool has in
no way diminished the importance of the Smith Chart. The Smith Chart has become
the ultimate background for both computer and measurement instrument displays.
Phillip Smith Beyond the Smith Chart
Had he not invented the Smith Chart, Phil would still deserve to be honored
for his many contributions to technology. Just before America's entry in World
War II, he was sent with a small group of engineers to Fort Hancock to work with
the Signal Corps Laboratories on a most important secret weapon - radar. He
spent a year on Sandy Hook designing antennas and related components for
production of the SCR-268 radar. Later, he worked on early microwave radar
antenna developments for submarine use under W.H. Doherty at Whippany, NJ. In
his early professional career, while developing 500 kw coaxial line components
for radio station WHAS in Louisville, Kentucky, he obtained a basic patent on
the optimum conductor diameter radio for a coaxial transmission line. This is
the outer to inner diameter ratio of a coaxial line which results in maximum
power handling capability for a given outer conductor diameter. Smith said this
was one of the simplest patents ever granted - the only claim was the single
number 1.65. Another basic patent he obtained was for the adjustable matching
After World War II he worked on the design of FM broadcasting antennas for
Western Electric broadcasting equipment. During that period he invented the
famous "Cloverleaf" antenna. Later he became involved in military
weapon radar systems studies and designed and supervised groups responsible for
the electrical design of the DEW LINE, NIKE ZEUS and the ABM System, which
One of the programs he worked on that can help to illustrate his creativity
in microwave technology was an acquisition radar system on the Island of
Kwajalein, in the South Pacific. This was an experimental system in the early
days of the SAFEGUARD program. The design of the antenna involved using a
Luneburg lens technique. The classical Luneburg lens is a spherical lens that
has the property that when the lens intercepts a plane wave, the focal point of
the wave will always appear at a point perpendicular to the wave itself on a
line through the center of the sphere at a point on the opposite surface of the
sphere, regardless of the direction from which the plane wave approaches the
This made it possible that when a signal was received, by virtue of the
location of the receivers and the action of the Luneburg lens, one could
determine the azimuth and elevation of the target.
The technique that was used at Kwajalein was to build one half of the sphere
- that is a hemispherical Luneburg lens - with a ground plane significantly
larger than the diameter of the sphere itself. The lens was made up of a series
of polyfoam cubes about 2' x 2' x 2' loaded with aluminum slivers, so that the
polyfoam block had a uniform dielectric constant throughout. By varying the
amount of aluminum slivers, one could vary the dielectric constant of the block.
The required values of dielectric constant were then determined to achieve the
Luneburg lens performance. It turned out for their system they needed about 10
to 12 different values of dielectric constant and perhaps dozens of each value.
The system worked as predicted by theory.
The operation of the antenna relied on the ability to build the homogeneous
aluminum-loaded polyfoam blocks of different, but precise dielectric properties.
The idea for the blocks came from Phil. This episode helps to highlight one of
Phil personality traits. As a friend of his commented, "he could be oh so
stubborn." And "on occasion that stubbornness had a profound effect."
Against the wisdom of some of the most distinguished consultants at Bell Labs,
Phil maintained that by the random distribution of the aluminum slivers the
dielectric constant could be controlled both as to homogeneity and value so as
to serve the needs of the project. The test proved he was right.
Phil married Rosine Rittenhouse around 1930. They had three children.
Donald was born in 1932 and is currently a Pastor. Stephen, born in 1936, is an
engineer and founded Basic Research Corporation in 1993. A daughter, Sharon, was
born just after the war.
Stephen recalls that around 1945 Phil used surplus components to assemble a
television on top of a card table in their home. NBC was broadcasting 1 to 2
hours a night on channel 4 out of New York. As town folk regularly gathered to
view the new marvel, Phil enclosed the entire table top to prevent contact with
the HIV circuitry. Phil also had an interest in building boats, usually small
boats with outboard motors.
In 1950 Phil took up private flying, eventually purchasing his own plane.
He loved to fly and accumulated over 1500 flight hours in the U.S., Bahamas,
Cuba, Mexico and Canada. On one eventful trip to Lexington, Phil, with son
Stephen and Wally Smith (an unrelated coworker), ran afoul of a weather front
and was forced to make an ungraceful landing in New London, Connecticut. Wally
apparently refused to fly with Phil again.
Phil was continuously active in the IRE and later the IEEE from 1947 on.
Phil served on and chaired numerous IEEE committees, including technical
standards Committee 2 on Antennas and Waveguides. In 1952 he was elected IEEE
Fellow "for his contributions to the development of antennas and graphical
analysis of transmission line characteristics." He was secretary-treasurer
of the Antennas and Propagation Society in 1954. He is a past member of
Commission 6 of URSI, and a member of the Delta Chapter of Tau Beta Pi.
In March of 1958, he and his bride, Anita Macpherson from Maplewood, New Jersey,
flew in their private plane to Cuba for a honeymoon. In 1964,
their daughter Penny was born. Penny is also an electrical engineer.
Toward the end of his career he continued to work as an individual
contributor. Although he had the perks of a supervisor, he chose not to be a
manager. His function was to look at anything and everything and contribute.
And he did, in the very best sense of the word. He was completely happy in his
He was a hands on engineer and was not particularly mathematical. When he
had a problem to solve and recognized that he needed some special help, he would
not hesitate to seek it out. He was highly organized and super meticulous.
When he was sure he was right, there was no way to make him back down.
The first edition of this book Electronic Applications of the Smith
Chart in Waveguide, Circuit, and Component Analysis, was published by
McGraw-Hill in 1969. He also authored an article on the Smith Chart for The
Encyclopedia of Electronics published by Reinhold Publishing Company in 1962
and 35 papers on antennas and transmission lines. Phil has 20 U.S. patents in
the microwave field including the basic patent on the transmission line matching
stub, the Cloverleaf antenna, and the optimum power ratio coaxial transmission
line. Phil retired from Bell Labs in 1970.
At its annual symposium in 1975 the MTT presented him with a Special
Recognition Microwave Application Award for his invention and application of the
The Smith Chart was eventually manufactured and sold by at least two
companies. When Phil retired from Bell Labs he organized Analog Instruments
Company of New Providence, NJ - which initially merchandised simple navigational
instruments for light aircraft, but later began supplying his charts and a dozen
or more chart-related items. Through 1975 Analog Instruments has sold about 9
million copies to engineers and educators all over the world. The Smith Chart
is currently selling at the rate of about a ton per year. The company is still
operated by his wife Anita.
Phil Smith passed away on August 29, 1987.
In 1989, the 50th anniversary of the Smith Chart was celebrated at the MTT
International Microwave Symposium in Dallas, Texas. Much of the material in
this biography was taken directly from material prepared for that celebration.
In 1994, Phil was elected to the New Jersey Inventors Hall of Fame.
I would like to thank Phil's wife Anita for providing much of the material used
in this biography. Portions were taken directly from material prepared by
Theodore Saad, Robert Mattingly, George Dale, and the Microwave Journal.
Other details were provided by Stephen Smith.
Editor's Note:Randall W. Rhea's biography of Phillip Smith is taken (with permission) from
a book by Phillip Smith titled Electronic Applications of the Smith Chart. This book was
published by Noble Publishing in 1995, with a second edition in October 2000.
This beautiful quilt was made by Cynthia Furse,
an Associate Professor in the Department of Electrical and Computer Engineering at
Utah State University. She has her students sign when they have finished their MS or BS design projects.
Neat idea, Cynthia -- thanks for sharing it with us!