IEEE - Aerospace and Electronic Systems - January 2023 - 70

Feature Article:
DOI. No. 10.1109/MAES.2022.3231045
The Radar Festival on the Rhine: A Highlight in the
History of the IEEE AESS
Wolfgang Koch , Fraunhofer FKIE, D-53343 Wachtberg, Germany
INTRODUCTION
Few inventions of the 20th century were as momentous as
Christian H€ulsmeyer's (1881-1957) " telemobiloscope, " the
original radar. Just 22 years old, the young high-frequency
physicist claimed to be able to reliably locate distant ships
even in darkness and fog with the help ofhis invention. His
" artificial sense organ " not only opened up a fundamentally
new dimension ofperception and but also increased the performance
ofnaturally existing senses.
In this way, H€ulsmeyer set the course that led to the
artificially intelligent production of situation pictures to
enable well-founded decisions in countless applications. It
is true that every living creature combines impressions of
its senses with already learned knowledge and messages
of other living creatures to gain orientation for appropriate
action. Without the technical enhancement of this ability
far beyond the natural level, however, we would hardly be
able to act in the complex technosphere of the modern
world that surrounds us ever more densely. In this respect,
H€ulsmeyer may be called one of the very early pioneers of
digitalization.
At first glance, this great moment in the history of
technology by the Cologne Cathedral Bridge, presented
to an astonished public then, may seem rather modest
today. On 17 May 1904, H€ulsmeyer pointed the antennas
of his telemobiloscope at the River Rhine-and sure
enough, as soon as Rhine ships approached, they reflected
the waves emitted from their metallic structures. The
sensing apparatus, now on display in Munich's Deutsches
Museum, one of the world's largest science and technology
museums, received the reflections of the ships. In
addition, a bell sounded to report them. The device also
Author's current address: Wolfgang Koch is with
Fraunhofer FKIE, D-53343 Wachtberg, Germany (email:
Wolfgang.Koch@fkie.fraunhofer.de).
Manuscript received 25 August 2022; accepted 25
August 2022, and ready for publication 27 December
2022.
Review handled by Hugh Griffiths.
0885-8985/22/$26.00 ß 2022 IEEE
70
indicated the direction from which they were approaching.
The detection range of about 3 km gave an idea of
the distance [2].
The " K€olner Tageblatt, " a local newspaper, reported
the day after
The apparatus worked extremely precisely. The
inventor explained also that a non-metallic target
reflects the electric waves, which could propagate
through the wall of the hotel and act in the
same way as before without obstacles. The spectators
felt that they were witnesses of the first
demonstration of one of the most important
inventions ofour time.
The international engineering community indisputably
dates the discovery of radar to 17 May 1904, in Cologne.
Today, H€ulsmeyer's first use case is just one of countless
applications of radar technology. It contributes to the
safety and smooth operation of complex air and water
infrastructures worldwide.
INVENTION VERSUS DISCOVERY
In view of the fact that Heinrich Hertz (1857-1894), the
discoverer of electromagnetic waves, held a professorship
in physics at the university in nearby Bonn, formerly the
seat of the Cologne Prince Electors, radar may be seen as
a thoroughly " Rhenish " invention. The difference between
the discoveries of scientists and the inventions of engineers
are well illustrated by the example of the different
personalities of Hertz and H€ulsmeyer.
A discovery concerns something that already exists,
which was hitherto unknown and whose usefulness is
still undetermined. As a result of the discovery, nothing
changes except the associated increase in knowledge of an
individual or the general public. In this sense, the Scottish
physicist James Clerk Maxwell (1831-1879) discovered
the equations that were later named after him, based on
other discoveries. Heinrich Hertz, in turn, was the first to
succeed in experimentally generating and detecting
IEEE A&E SYSTEMS MAGAZINE
JANUARY 2023
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IEEE - Aerospace and Electronic Systems - January 2023

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