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3&

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(1962).

Karl Jansky: His Career
at Bell Telephone Laboratories

In 1928, 22-year-old Karl Jansky
joined my group in our Cliffwood field
laboratory and, because he had a
chronic kidney ailment, it was _re-
quested that he be assigned to work
which would not exert undue pres-
sure on him. (Jansky was first re-
jected by the Medical Department but
later was accepted through the inter-
vention of his brother.)

Karl agreed to start work recording
the static received at long wave-
lengths, using equipment already in
existence. Later, he planned to record
static at 14 meters’ wavelength, using
a 100-foot-long “Bruce” antenna which
was to be mounted on a rotating
platform such as we had used in
1924 to study long-wave static. He
built an ultrasensitive shortwave re-
ceiver similar to the one I had used
in 1928 to show that Johnson noise
limits the sensitivity of radio re-
ceivers. He also modified Mutch’s
static recorder, which was an improved
version of the one that had been used
earlier to record long-wave static:

After working with his colleagues,

 

Dr. Friis, prior to his retirement from Bell
Telephone Laboratories in 1958, was director of
the radio laboratory at Holmdel, New Jeracy,
for many yeats. He resides at 30 River Road,
Rumson, New Jersey.

20 AUGUST 1965

Harald T. Friis

especially Beck, Mutch, and Sharp-
less, to become thoroughly familiar
with the then-existing techniques for
accurate measurement, Karl began to
assemble the equipment, but his work
was interrupted by the relocation, in
January 1930, of the whole Cliffwood
field laboratory to Holmdel.

Karl had a new rotating platform
built at Holmdel and reassembled his
equipment. By the end of 1930 he was

‘ready to record static at 14 meters’

wavelength.

His recordings gave him lots of
data, and he published the results
in a paper, “Directional studies of
atmospherics at high frequencies,” in
Proceedings of the Institute of Radio
Engineers for December 1932. In this
paper he classified static into three
types: (i) that due to local thunder-
storms, (ii) that due to distant thunder-
storms, and (iii) “a steady hiss static,
the origin of which is not known.”

The hiss-type static, or hiss noise,
fascinated Karl. The angle of arrival
did -not seem. to check with anything
pertaining to the earth or the solar
system. Having collected thousands of
records, he discussed the data with his
colleague A. M. Skellet, who was fa-
miliar with astronomy. The conclusion

Sale
Wn.

61. Chiao, Garmire, Townes, Proc. Course XXXI,
Enrico Fermi International School of Physics
(Academic Press, New York, 1964).

62, Chiao, Townes, Stoicheff, Phys. Rev. Letters
12, $92 (1964).

63. C. H. Townes, in Quantum Electronics, C. HL
Townes, Ed. (Columbia Univ. Press, New
York, 1960), p. 402; C. Kittel, Phys. Rev.
Letters 6, 449 (1961).

64. E. B. Tucker, Phys.
(1961).

65. L. Brillouin, Ann. Phys. Paris 17, 88 (1922);
M. Born and K. Wang, Dynamical Theory of
Crystal Lattices (Oxford Univ. Press, New
York, 1964).

Rev. Letters 6, 547

was that the hiss noise came from the
Milky Way.

Karl presented the findings before
the International Scientific Radio Un-
ion (URSI) in April 1933, in Wash-
ington, and published a paper, “Elec-
trical disturbances of extraterrestrial
origin,” in Proceedings of the LR.E.
for October 1933. He also published
a short paper, “Radio waves from
outside the solar system,” in Nature.
The Bell Telephone Laboratories pub-
lications department issued a press re-
lease, and the New York Times carried
the story as front-page news.

As a result of this astounding and,
to most people, unbelievable discov-
ery, Karl was now a famous man.
Karl was modest, and this adulation
did not affect him. He wanted to con-
tinue his work and thought that it
would be worth while to look for hiss
noise at a shorter wavelength.

By 1931 Karl had built a new re-
eeiver that covered the wavelength
range 4 to 20 meters, and he used it
to observe static from local thunder-
storms. A. C. Beck erected a 100-foot-
long comb-type antenna on Karl's ro-
tating platform and, in 1934, Karl con-
nected his receiver to the comb an-
tenna, but found no hiss noise at a
wavelength of 4 meters. In retrospect,
this is not surprising since the gain of
the comb antenna is low (its direc-
tivity gain is high). .

-In July 1935 Karl presented a pa-
per, “A note on the source of inter-
stellar interference” (Proceedings of
the LR.E., October 1935), in which
he pointed out that the hiss noise was
strongest when the antenna beam
pointed toward the center of the Milky
Way, and that the hiss noise sounded
like thermal agitation neise. Kari had,
in the meantime, made many mea-
surements of the noise output of large
fixed rhombic antennas; he always
found hiss noise appearing at that time
of the day when the antenna pointed

“1

t

ib
JOSHUA LILES

 
v-

toward the center of the Milky Way.
These observations confirmed his ear-
lier results, and be stopped making
them at the end of 1936.

Karl had been an instructor at the
University of Wisconsin for a year
before he came to Bell. and he liked
teaching. A. C. Beck had the same
background at Rensselaer Polytechnic
Institute, and he also liked teaching.
Both he and Karl accepted gladly the
additional job of teaching courses to
our technical assistants and often
talked about taking teaching jobs.
Beck recalls discussing an opening at
Iowa State College in 1936, but they
both agreed that, in spite of the cur-
tailment in research activity and their

. low pay due to the depression, they

were better off at Bell Telephone Lab-

. oratories.

Karl consolidated his findings on
hiss static, or what he was then call-
ing “star noise,” in a paper, “Mini-
mum noise levels obtained on short
wave receiving systems,” which he
presented before the April 1937
URSI meeting in Washington (Pro-
ceedings of the I.R.E., December
1937). This paper also included a
study of man-made diathermy inter-
ference. Karl had by now, as a side-
line, become an expert on receiver
sites; for example, he recommended
the Manahawkin site for Teception of
transatlantic short waves.

Karl, being a good research man,
then became interested in the charac-
teristics of the several different kinds
@f noise, thermal noise included. He
@id some excellent experimental work
and presented his results in a paper,
“An experimental investigation of the
characteristics of certain types of
noise,” at the April 1939 URSI
meeting in Washington (Proceedings of
the I.R.E., December 1939),

In 1938, Karl dropped the study

of star noise and, some 17 years later,
I was criticized by people who thought
that I had stopped him. This was not
true. Karl was free to continue work
on star noise if he had wanted to, but
More than 5 years had passed since
he made his epochal discovery, and
not a word of encouragement to con-
tinue his work had appeared from sci-
entists or astronomers. They evidently
did not understand its significance.
Also, Karl would have needed a large

842

steerable antenna to continue his work,
and such antennas were unknown to
ws at that time. Radio astronomy, as
such, did not then exist, and neither
Karl nor I had the foresight to see it
coming some 10 years later.

What actually happened was that
Karl, who had worked for 10 years
on the angle of arrival of noise and
interference, now expanded his work
to measurement of the angles of ar-
rival of transatlantic radio waves. He
and a colleague, C. F. Edwards,
studied the angle of arrival of 16-
meter waves in 1938, and then began
a special radio propagation experiment
in January 1939, which resulted in a
Paper, “Measurements of the delay and
direction of arrival of echoes from
near-by short-wave transmitters,” pub-
lished in the Proceedings of the LR.E.
for June’ 1941, They also compared
reception at the Manahawkin and Net-
cong receiving sites in 1940.

It was an outsider, Grote Reber, an
ardent radio amateur, who took up
studies of star noise after having read
Jansky’s original papers, and in 1941
he succeeded, with improved equip-
ment and a 30-foot “mirror,” in map-
ping the Milky Way at 3 meters’ wave-
length. Karl was delighted that some-
body else had finally confirmed his
early work. John Schelleng, who
headed the Deal Laboratory, was
greatly impressed by Reber’s single-
handed and successful effort. He re-
calls that he told Karl that it was
too bad that he was not himself work-
ing in this field. To this Karl replied
cheerfully that after all he had
“skimmed the cream.”

The United States was then getting
into war, and all Holmdel personne]
worked 50 percent overtime on war
jobs (radars). Later, sensitive receivers
and large paraboloids became avail-
able, but nobody in my group, Jansky
included, could take time off from war
work to study star noise. During the
war, Karl made several valuable con-
tributions in classified areas and re-
ceived an Army-Navy citation for his
work.

My group turned back to communi-
cation research after the war and, since
microwave radio had looked promis-
ing even before the war, everyone con-
centrated his research on microwave
transmission and microwave repeaters.

i

Being familiar with the importance of
minimum noise levels in receivers,
Karl selected this phase of microwave
repeater research and worked on in-
termediate frequency amplifiers in
1946 and 1947. Our work resulted in
an important paper, “Microwave re-
peater research,” by H. T. Friis in the
Bell System Technical Journal for
April 1948. Karl contributed the sec-
tion on intermediate frequency ampli-
fiers, edited the whole paper, and
Presented it before the Monmouth
subsection of the Institute of Radio
Engineers.

A chore that Kar! did not mind was
visiting his old alma mater, the Uni-
versity of Wisconsin, in 1947 and
1948, to recruit new employees.

I was made director of radio re-
search in 1946. As a result of the re-
organization this entailed, I asked Karl
to join G. C. Southworth’s group in
January 1948. The era of transistors
was just emerging, and Karl included
them in his experiments with ampli-
fiers. Karl, naturally, also showed in-
terest in the new field of radio as-
tronomy. He wrote, for example, a
detailed report on a conference that
he attended on this subject at the
Naval Research Laboratory in May
1948.

Karl’s health had in the meantime
declined somewhat. He was out on
extended sick leave in 1945 and 1946.
He spent 4 days in the spring of 1948
at Durham, North Carolina, for medi-
cal tests, and went back in the fall
for medical treatments. By the end of
1949 he was really sick. He died 14
February 1950, and I lost a close
friend.

After the war, radio astronomy
Started throughout the world, especially
in Australia, England, and Holland.
Ewen and Purcell made their impor-
tant contribution of the 1420-maga-
cycle hydrogen line in 1951. After a
conference in Washington in 1954,
large-scale work started in the United
States.

It is unfortunate that Karl did not
live long enough to see the unbeliev-
ably important results of his early dis-
covery. He is now recognized as the
father of radio astronomy, and I am
proud of having been associated with
the man who deserved, but never got,
the Nobel prize for his discovery.

SCIENCE, VOL. 149