November 1935 Radio-Craft
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
The announcement and public demonstration
of Senatore Guglielmo Marconi's "death ray" device was the coming true of some of
the worst fears of science fiction aficionados. Application of these newly created
centimeter−wave "beams" could roast the flesh of man or beast when supplied with
great enough power. The diminutive wavelength not only would heat liquids, but also
provided a means of detecting and measuring energy reflected off of "targets" such
as aircraft and boats. Its applications were endless. Although not called so, one
of this 1935 Radio−Craft magazine article's diagrams looks to be an example of a
system. The early magnetron implementation is quite different than the modern cavity
arrangement. The page to the left is the one referenced in the article.
The New "Mystery Ray"
The ray transmitter with the dipole antenna at left.
This new ray - developed simultaneously by three World Powers - depends upon
the beam-effect and reflection of "centimeter"-length or ultra-ultra-short waves
to "spot" enemy planes, ships, etc. Fortunately, there are valuable commercial applications
for this new tool of warfare and destruction.
In the past half-year many exciting reports have been published concerning a
new invention, which may be used to produce the most perilous of all war weapons,
the often predicted - but never presented "death rays." Comments from experts concerning
these exciting reports have firmly indicated that death rays are mere daydreams,
at least on the basis of present technical progress, and that the existence of these
"extremely dangerous" rays may fit well into the realms created by Hollywood studio
facilities but not in the world of realities.
The public mind, however, fascinated by the horrible prospects of these death
rays in a future war, took these unconfirmed reports as scientifically verified
facts and mystery story authors even started at once to lubricate their typewriters
and do their part in confusing the public mind!
Receiver for the rays.
Split-magnetron sending-receiving tube.
Construction and circuit of the "split magnetron".
The transmitter compared to match box.
Dipole antenna for transmitter.
Dr. S. Spitz, of Burbank, California, developed this amazing
machine, which indicates as a moving spot of light, the location of an airplane;
the 'plane's sound automatically actuates the device. The same principle probably
could be applied to silent 'planes, the actuation then being obtained by means of
centimeter (the "mystery ray" mentioned in this article) waves reflected from the
How the ray shows the location of enemy aircraft.
This, quite muddled, situation has recently been even more confused by an interview
given to the press by Senatore Guglielmo Marconi concerning a new kind of ray, of
which he predicted some extraordinary possibilities through their application in
case of war. This interview by the head of Marconi Wireless Ltd. induced its competitor
in the world market, the German Radio Corporation (Telefunken Company), to unveil
some results of their recently finished secret experiments with a kind of ray similar
in its qualities to the mystery rays of Marconi.
According to recently printed newspaper reports the U.S.A. Signal Corps also
has a mystery ray device in development, which seems to be equal in its qualities
to the German and Italian ones. The kind of rays and devices used by the Signal
Corps could not be learned, since all details concerning the devices made by the
General Electric Co. have been enveloped in great secrecy. While the Signal Corps
conducted its first practical tests at the Lighthouse Station on the Navesink Hills
near Highland, N.J., a heavy military police line was thrown around the station.
These circumstances make the demonstration of the German mystery rays, recently
conducted in a suburb of Berlin especially interesting. These demonstrations disclosed
to the invited newspapermen, and foreign military attaches, contrary to all expectations
- were not units of tremendous dimensions, but tiny devices about as large as a
normal match box! The new mystery-ray machines do not operate as has often been
predicted with millions of watts, but radiate only a few watts in the form of very
short waves (from 5 to 15 centimeters) into the "air." The energy necessary to operate
these mystery ray transmitters is provided by regular dry-cell batteries of normal
size and weight. The produced beam radiated by these transmitters is as narrow and
"confined" as a water pipe of ordinary dimensions, and despite the fact that they
are not really death rays, in the sense fiction story writers put it, they are actually
able to bring death and destruction to ships and aircraft.
Experimental magnetron tube transmitter.
Transmitter with "wing" reflector.
The reason for this ostensibly seeming paradox is explained by the fact that,
although these rays do not kill or destroy directly they do so indirectly by furnishing
the means to detect and localize airplanes even if hidden by clouds, smoke, snow
It is said that these valuable uses are possible through the ability of the mystery
rays to penetrate the sight obscuring elements without being absorbed or dispersed
as would be the case if a normal light beam (and under certain circumstances, even
a strong beam of ultra-red light) was used. These newly utilized rays have, however,
the advantage of being as easily reflected as a normal light beam. How these qualities
of the newly utilized "ultra-ultra" short-waves may be used for air defense will
be shown by the following example.
Along the borderline of the country a great many of these small, mystery-ray
transmitters will be fixed atop cast-iron posts or, perhaps, hidden on church towers
or tall buildings. The transmitters are so adjusted that their beams are radiated
at a slight angle into the sky. Any airplane flying through these invisible "feelers"
will reflect the beam back to earth. Since these beams obey the well known optical
law, that "the angle of reflection is equal to the angle of incidence," it is easy
to install a great many of these receivers in such close proximity that at least
one of them may be depended upon to pick up the reflected beam, regardless of how
high or how low the plane flies.
Tugboat being guided into a harbor.
Since the use of so many receivers might create some difficulties in controlling
them all at the same time (which is necessary for an efficient air defense) an automatic
system, operating similarly to the relays used in automatic telephony, to connect
two telephones without help of human hand, will be developed. The various transmitters
will be modulated by certain current impulses, and if such a succession of impulses
is received, the "telephone" relay will indicate the position of transmitter and
the receiver in operation upon a kind of annunciator.
These rays are produced by tiny split-plate magnetron tubes (The split-plate
magnetron is illustrated and described in considerable detail in the article, "Super-short
Radio Waves," which appeared in the October, 1934, issue of Radio-Craft. - Editor),
which are also used for the reception of these rays. The electro-magnet used for
these transmitters is of surprisingly small dimensions but produces (through the
application of a special high grade of iron) a remarkably strong magnetic field.
The new German ultra-ultra-short-wave receivers and transmitters have been developed
by the Drs. H. Scharlau and W. Runge, of the Telefunken Laboratories. As Dr. Runge
recently demonstrated, these newly utilized rays may be of great value in piloting
incoming ships into foggy harbors. For this purpose two parallel "running" beams
are radiated by two transmitters with any desired spread between them. Two receivers
are installed aboard the ship to be piloted which are connected to a pilot indicator
instrument by means of a bridge circuit. As long as the ship follows the proper
direction, the indicator of the pilot instrument will stay at the "on course" line.
If the ship shifts more to one side, thus leaving the proper direction, the field
strength of one of the very sharply concentrated beams will rise, while the other
beam will be received with decreasing strength.
The mystery-ray devices might also be useful for private telephone connections
between two points as far distant as sight is possible. If receiver and transmitter
are installed on high points, the maximum bridged distance will approach 50 miles.
The communication can be kept secret because no reception outside of the very narrow
"beam line" between transmitter and receiver is possible.
Posted January 2, 2024
(updated from original
post on 9/7/2015)