



by Thomas J. Naughton



“All right, gentlemen. Ready!”

At the words, the savants, like Statues of Liberty, raised their light-bulbs overhead and held them there. The engineer flicked a switch, swung the big horn to point toward them; pivoting smoothly, the big horn came to rest focused on the cluster of bulbs. And as it did so, every one of the bulbs lit up.

No wires, except for the little tail-like antenna, were attached to those lamps. They contained no batteries, they were entirely unconnected to any source of power. Yet they were alight. How?

The answer to that question records the achievement of a goal, a Promised Land of Science that has been sought for 40 years. It is something new under the sun. For those lamps were receiving power from the big horn, through the air. Power, in that laboratory, was being broadcast.

Those little lights, shining in a prosaic laboratory, marked the coastline of a new land. No powerlines march Indian-file over the hills and through the valleys of that land; no wirepacked conduits lie buried under the streets of the cities; no third-rails or overhead wires parallel the railroad tracks. The people there do not need those things, for they can tune in a supply of power as easily as we tune in a radio program.

There are no gas stations in that land. Automobiles have no gas tanks, no batteries; driven by electric motors, they draw their power from the airwaves. Airplanes are free from the leash of limited fuel capacities, for they carry no fuel; they can fly from New York to Hawaii, to Hong Kong, to India, with never a stop.

Houses have no furnaces, no oil burners, no steam pipes or radiators; they are heated by electrically-activated coils set in the walls. Power is everywhere, in the air itself, always available, waiting only to be funneled out through a strand of wire and put to work in a thousand ways.

That is the land whose first dim outlines were picked out by the light of the little lamps in that laboratory. It is the El Dorado for which cranks, dreamers and geniuses alike have been looking for two generations.

Our passport to it is the pair of doughnut-shaped copper containers manipulated by that Westinghouse engineer. Separately, the containers are called rhumbatrons; together, with a copper pipe connecting them, they form an invention which has been authoritatively described as “the most important advance in radio since the invention of the audion in 1906”: the Klystron.

For the Klystron, newborn though it is, has already proved itself the wonder-child of electrical technology. Probably no other invention of recent years has been the master-key to so many doors, has swept away obstacles from so many different paths of progress. Broadcast power is only one of the great vistas opened up by the Klystron; other fields in which advances are already being made with it are airplane travel, telephony, and television; and it is an important new tool for national defense.

Yet for all its versatility the Klystron, like most great inventions, is essentially simple; , it consists chiefly of nothing more complicated than two oscillating magnetic fields. Through the first field, in rhumbatron No. 1— called the “buncher”—a stream of electrons is squirted from a cathode; the field, shuttling rapidly back and forth, alternately speeds up and slows down the electrons passing through it so that they emerge from it not in a steady stream, but in bunches, with empty spaces i between. These bunches of electrons, traveling at a clip of 25,000 miles a second, shoot through a copper pipe to the second rhumbatron, the “catcher”; there they hit the ; second, or backstop, magnetic field, which absorbs their motion -energy and converts it into high-frequency radio waves. These are the waves of power.

The whole process -takes place inside a space no larger than that occupied by a portable radio. A Klystron, complete, weighs only about five pounds. Even the name of it and its parts are, as scientific names go, compact and simple; the rhumbatron is so called because of the rhythmic motion of the magnetic field inside it; “Klystron,” derived from Greek, signifies “waves breaking on a beach”—a phrase which pictures very aptly what happens in the “catcher” rhumbatron.

But the waves produced by the Klystron are different from any ever known before. The Klystron waveband is narrow—the wavelength is from one centimetre to one metre—but there is room in it for about 500,000 separate signals, as compared to about 100 separate signals possible in the standard 200 to 450 metre band. Also, the Klystron wave travels through air in a straight line; it does not follow the curvature of the earth, and it goes through the Heaviside Layer, that mysterious ionized stratum which serves so usefully as a backboard for all other radio waves, like a bullet through cardboard. If directed into a copper pipe, however, it will flow in that pipe like water, even around turns.

These characteristics cause communications engineers to regard the Klystron as being little short of a gift from heaven. Because of the enormous multiplicity of its signals, they believe it will soon enable them to transmit as many as 500,000 telephone messages at once on a single cable. Then all the long-distance telephone calls in the country could be handled by one or two main trunk lines with comparatively short tributary branches. Messages from New York to Pittsburgh, Chicago, Denver, and San Francisco, for ex- ample, could all be poured into the same cable; those bound for the inland cities could be unerringly picked out of the crowd at the right time and shunted off to their proper destinations while the others shoot through. Television engineers expect to use the Klystron similarly, so that the cost of television networks—up to now so huge that no such network has ever been formed—can be cut to a fraction of its present figure by transmitting many programs through a single copper pipe.

In short-distance communication the possibilities opened up by the Klystron are even greater, for it may in most places actually eliminate wires altogether. Wires are not needed in this age of radio for transmitting messages; that is being done without wires all the time. Where there are a great many messages, however, wires are necessary to keep them separated, because without wires only as many different messages could be in transit at any one time and place as there are distinguishable wavelengths available— under present circumstances, a few hundred. But the Klystron makes possible half a million simultaneous messages, each distinct from all the others, without wires. That is to say the Klystron makes possible, for all except the very largest cities, radio telephone.

Your radio telephone will have two parts: a receiver, set at a fixed wavelength which will be your telephone number; and a transmitter, ajustable by a dial to whatever wavelength you want to call. You won’t have to worry about eavesdroppers, because no receiver will be able to pick up any messages not tuned to its own built-in wavelength, and all the receiver wavelengths in any one community will be different. One city’s system will not cut in on that of any other city, as long as the two are at least 200 miles apart, because the Klystron wave travels in a straight line in air, and therefore cannot be tuned in beyond the horizon as seen from the transmitter. The short-range receivability of the Klystron wave, which appears at first glance to be a limitation, is actually an advantage.

Nor is its straight-line travel an advantage only for radio telephony; it combines perfectly with two other characteristics of the Klystron wave to make the instrument a powerful tool both for safety in air travel and for national defense. One of these characteristics is so remarkable that, if the Klystron had nothing else to recommend it, it alone would be enough to ensure the invention an important place in engineering history. It is that Klystron waves can be focused with precision on an objective—not merely directed in a general way, like present-day airlane “beams,” but aimed at a point. The airlane “beam” is a cone, fanning out from the source; the Klystron beam is extremely narrow and can be shot out like the ray of a searchlight.

Already that controllable precision has been put to use where it was badly needed. The Klystron is the heart of a new blind-landing system for airplanes, a system as superior to all previous ones as a modern pursuit ship is to a jenny. For even the best of the older systems had serious faults; they were not thoroughly reliable under all conditions and, even under the best conditions, most of them were fantastically complicated. The Klystron beam system, simple, boring through static like a high-speed drill, has solved the problem. Army and Civil Aeronautics Authority planes, using it, have made more than 1000 blind landings in all kinds of weather, and every one of them has been perfect.

Although the Klystron beam penetrates electrical disturbances and the Heaviside Layer with undeviating ease, however, it will not go through any substance which is not a good conductor of electricity. Whenever it hits an electrically-resistant surface, it bounces back from it like light from a mirror. This is another apparent liability which is in fact a considerable asset.

For because of it the pilot aloft in dirty weather can use the Klystron to shoot a beam downward and, by measuring the time it takes to rebound, determine a vital fact no altimeter can tell him: his exact distance from the ground. Over rough country he can shoot a Klystron beam ahead, and with it feel his way past shrouded mountain peaks.

And if he can see mountains, he can see other planes. Reports of R.A.F.’s new radio-rebound device to increase the effectiveness of fighter planes against night bombers indicate that the Klystron is doing its part to keep the Luftwaffe out of English skies!

In the improvement of ground defenses against aircraft, the Klystron is proving invaluable. Antiaircraft watchers probing opaque skies with its far-reaching, invisible finger can spot approaching planes long before any sound of motors could be picked up by even the most sensitive microphones. The Klystron can aim and fire guns automatically in pitch darkness with greater accuracy than human gunners can achieve on a clear day!

In that field the Klystron jumped to maturity almost as soon as it was born. But in other fields, in which it remains still an infant, it will attain the greater stature. It grows toward the day when wires, now vital nerves of civilization, will be left to moulder in forgotten conduits; when your telephone, your stove, your heating plant, your light —all will inhale power through an antenna on your roof. Automobiles, airplanes, trains, ships, will ride the pulsing power in the air like surf-boarders on the crest of a wave—the wave of the future, which will emanate from a couple of copper doughnuts called a Klystron.

  1. EMFalk says: January 6, 201211:46 am

    Their ‘vision’ was 30 years too late:…
    And, of course, Tesla had a relationship with Westinghouse at on time. Hmmmmm…..

  2. Hirudinea says: January 6, 20123:03 pm

    Like Westinghouse told Tesla about broadcast power “I can’t meter it.”

  3. Hip2b2 says: January 6, 20123:11 pm

    Not only was power broadcast, so were thought waves; as it was Kylstron technology that ran the Forbiden (Krell) Planet:

    “The big machine… cubic miles of Klystron relays… enough power for a whole population of creative geniuses… operated by remote control.”

    What an opportunity we seem to have missed.


  4. Stephen says: January 7, 20126:17 am

    The machine which powered the RAF radar sets was the magnetron, not the klystron.

    This article interests me particularly because of the resemblance to the technology in Robert Heinlein’s excellent story “Waldo”. This also foresees a world with broadcast power, and even the telephone with the “double dial” described above. I suspect Heinlein had read this exact article. However, it’s not a paradise: it turns out that living in a world saturated with microwaves is gradually sapping everyone’s strength, and they have to find an alternative before the human race ends up too weak to move.

  5. JMyint says: January 7, 20121:54 pm

    Modern Cell Phones rely on Frequency Shift Keying where the signal changes frequency several times an second. The technology was patented by a lovely lady by the name of Hedwig Keisler Markey in June of 1942.

    The resonant cavity magnetron invented by Randal and Boot in 1940 in England had 600 times the ouput of the Klystron tube and allowed for the creation of compact, high powered, and high resollution radar sets.

  6. Casandro says: January 8, 20126:03 am

    Well of all the ways to transmit energy wirelessly, Klystrons probably are the worst. As you are in the microwave band, absorbtion is high.

    BTW you are wrong about cellular phones, in fact the analog cellular phone standards typically already used one frequency pair per call. Only with digital standards multiple calls use one frequency.

  7. toomuchtelly says: January 8, 20128:16 pm

    I remember that the T.V. show “The Avengers” from the 60’s had an episode about a “portable energy broadcasting machine” just like the one in this advert.
    Also as has been said already “Tesla and Westinghouse” coincidence?Maybe old Tesla wasn’t as mad as he’s made out to be.

  8. JMyint says: January 9, 20123:33 pm

    Cassandro, I doubt that you would find an analog cell service in North America or Europe today. As for the other.…

  9. JMyint says: January 9, 20123:34 pm


  10. Casandro says: January 10, 20121:49 pm

    @JMyint: It was only turned off in the US a few years ago. Since there was no standardised digital cellphone service in the US, analogue networks were popular will into the 2000s.

  11. Goodnslo says: February 12, 20124:07 pm

    I like this article. Just needs some links to what the Klystron led to present day development. The Klystron was the workhorse for all RADAR and microwave communications during the WW2 and after. It lead to the development of the microwave ovens. Discovery of higher frequency bands and frequency switching technology in the phone network.

    As far as cellphone service, an old Elvis Presley movie utilized one in the late 40’s and early 50’s; even at that time it was considered for the elite and wealthy so was not widely supported.

    Per the article’s description of transmitted power, it’s funny what is old is new again in which some MIT students do the exact same thing at high frequencies.…

  12. Nomen Nescio says: February 12, 20124:49 pm

    klystrons powered most WW2-era radars, but not all. a British team had invented the magnetron shortly before, and the allies used it to good effect in short-wave radars.

    and that experiment with the wireless lightbulbs gives me the willies. if and when i ever notice i’m standing in a microwave field that could light up a bulb, i’m getting myself out of it, thank you very much. i don’t even care that it’s not ionizing radiation, i don’t want that sort of power levels through my body if i can help it.

  13. Jayessell says: February 12, 20126:40 pm

    By 1942 RADAR was no longer classified?
    (as both sides had it)

  14. Charlie says: February 13, 201210:01 am

    Jayessell » Actually during WWII the Allies used Cavity Magnetrons which were a big secret and a huge advantage. There is a really fantastic book I read a while back called The INVENTION THAT CHANGED THE WORLD: HOW A SMALL GROUP OF RADAR PIONEERS WON THE SECOND WORLD WAR AND LAUNCHED A TECHNOLOGICAL REVOLUTION. You wouldn’t think a book about the invention of radar would be very interesting, but I thought it was even better than The Making of the Atomic Bomb by Richard Rhodes. (Which is also an amazing read).

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