November 1935 Radio-Craft
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles
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 generated 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. It applications were endless. Although not
called so, one of the article's diagrams looks to be an example
bistatic radar system. The early magnetron implementation is
quite different than the modern cavity arrangement.
The New "Mystery Ray"
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.
The ray transmitter with the dipole antenna at
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.
Receiver for the rays.
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!
Experimental magnetron tube transmitter.
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
Split-magnetron sending-receiving tube.
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.
Construction and circuit of the "split magnetron".
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.
The transmitter compared to match box.
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 or rainfall.
Dipole antenna for transmitter.
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.
Transmitter with "wing" reflector.
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.
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
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
How the ray shows the location of enemy aircraft.
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
Tugboat being guided into a harbor.
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 September 7, 2015