This full-page advertisement by
Bell Telephone Laboratories in the June 1956 issue of Radio & Television
News magazine seems to imply that their Dr. S. Weisbaum and/or his
contemporaries was/were the original developer/s of the waveguide isolator. If so,
it would be no surprise since Bell Labs was responsible for many technology innovations
during its history - RF, microwaves, telephony, information theory, switching, transmission
lines, test and measurement, and much more. Other information available on the Internet
assigns credit to
Bell Labs in the same timeframe. From the ad: "This isolator is a slab of ferrite
which is mounted inside the waveguide, and is kept magnetized by a permanent magnet
strapped to the outside. The magnetized ferrite pushes aside outgoing waves, while
unwanted reflected waves are drawn into the ferrite and dissipated. Bell physicists
discovered this action during their fundamental studies of ferrites."
Bell Telephone Laboratories Isolators
Radio's One Way Street
Dr. S. Weisbaum assembles an isolator which he developed for use in a new microwave
system. Dr. Weisbaum is a Ph.D. in microwave spectroscopy from New York University.
He is one of many young men at Bell Laboratories applying the insight of the physicist
to develop new systems of communication .
New radio relay systems for telephony and television now in the making will employ
an ingenious device invented by Bell scientists. The device, known as an "isolator,"
senses which way microwaves are traveling through a waveguide, and stops those going
the wrong way.
In the new systems a klystron wave generator sends signals through a waveguide
to the antenna. The klystron must be shielded from waves reflected back along the
waveguide by the antenna. The isolator stops reflections, yet allows the transmitted
signals to go through clear and strong.
This isolator is a slab of ferrite which is mounted inside the waveguide, and
is kept magnetized by a permanent magnet strapped to the outside. The magnetized
ferrite pushes aside outgoing waves, while unwanted reflected waves are drawn into
the ferrite and dissipated. This "field displacement" action results from the interplay
between microwaves and a ferrite's spinning electrons. Bell physicists discovered
this action during their fundamental studies of ferrites.
This is another example of how Bell Telephone Laboratories research works to
improve American telephony and telecommunications throughout the world.
The heart of the isolator is a ferrite slab. Geometric pattern is a carbon layer
which dissipates reflected signals.
At a radio relay station an isolator assures one-way transmission from the output
of the amplifier to the antenna.
Bell Telephone Laboratories
World Center of Communications Research and Development
Posted May 3, 2024 (updated from original post
on 6/3/2018)
Bell Telephone
Laboratories Infomercials |
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Bell Telephone Laboratories - Time Domain Reflectometry - December 1948 Popular
Science
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The Future Holds Great Promise - August 1949 Popular Science
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Waveguide: 7/47 Popular Mechanics
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Wire Wrapping - 10/1953 Popular Science
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X-Rays, 4/60 Radio-electronics
- The Battle of
the Atoms, 4/1948 Radio News
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The Transistor, 6/1952 Radio-Electronics
- 90-Mile Laboratory
for Telephone and Television, 6/1945 Radio News
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Wire-Wrap, 10/53 Radio-Electronics
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EDT Crystals, 10/47 Radio-Craft
- Germanium Refining,
5/54 Radio & TV News
- Crystal Timekeeping,
1/46 Radio News
- Transatlantic
Cable, 11/56 Radio & Television News
- Pipe Circuits,
11/48 Radio & Television News
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Coaxial
Electron Tube, 6/54 Radio & Television News
- Thermocompression
Wire Bonding, 3/58 Radio News
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Radio Relay Stations, 8/52 Radio & Television News
- Isolators,
6/56 Radio & Television News
- Punch
Cards, 3/55 Radio & Television News
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Over-the-Horizon
Communications, 10/55 Radio & Television News
- Memory
Devices, 2/58 Radio & TV News
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Adventure in Silicon, 5/55 Radio & Television News
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6/55 Radio & Television News
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Project Echo, 11/60 Electronics World
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Testing Phones - November 1947 Popular Science
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Jacques Bernoulli, February 1960 Radio-Electronics
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Type-O Carrier System, October 1952 Radio-Electronics
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Electron Microscope, 4/1952 Radio-Electronics
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Thermistor, 11/1946 Radio-Craft
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Germanium Crystal, 1/1954 Radio-Electronics
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Lens
Antenna, 5/46 Radio-Craft
- Quality Control, 6/46
Radio News Article
- Transcontinental
Radio-Relay, 10/51 Radio & TV News
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Battery, 7/54 Radio & Television News
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Germanium Transistors, 1/54 Radio & Television News
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Magnetron, 10/45 Radio News
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The Cableman, 10/49 Radio & Television News
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Coaxial Cable, 12/49 Radio & Television News
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Tin
Whiskers, 12/55 Radio & Television News
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Contact Inspection, 7/55 Radio & Television News
- Transistor's
10th Anniversary, 6/58 Radio & Television News
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Wire
Wrapping, 10/53 Radio & Television News
- Junction
Diode Amplifier, 11/58 Radio News
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Nobel Prize Winners, 2/57 Radio & Television News
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Diode Speeds Voices, 8/58 Popular Electronics
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Microwave Relays, 7/59 Electronics World
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