IEEE Circuits and Systems Magazine - Q3 2022 - 51

Pioneers in CAS
Wilhelm Bader, a Pioneer of Network Synthesis
P
rofessor Wilhelm Bader was
born in August 1900 in Landau
an der Isar in Bavaria, Germany.
Towards the end of First World War,
he entered the army as a war volunteer.
From 1919 to 1923 he studied
electrical engineering at the Technical
University in Munich (TUM). After his
graduation he worked for the Siemens
Company in Berlin and from 1927 to
1939 as an assistant at the metrological
institute of TUM. In the early 1930's
he managed with friends to set free
again a professor of TUM, who was imprisoned
by the Nazis in the concentration
camp of Dachau. After Second
World War, this professor admitted that Bader has saved
his life and he handed over his vacation-house at one of
the Bavarian lakes to one of Bader's sons who was born
with Down syndrome.
While at Siemens Bader designed a circuit, which
Wilhelm Bader
allowed the simultaneous exact measurement of voltage
and current. In 1939 the Stuttgart Technical University
selected Bader as the successor of the famous
mathematician Fritz Emde on the chair of Theoretical
Electrical Engineering which Bader extended to Circuit
Theory and Network Synthesis. In this synthesis
category Hans Piloty, a professor at TUM, had published
a method to mathematically determine for a
given matrix of a system with only lossless components
the minimal number of components necessary
to realize the matrix. The result included components
with tightly coupled transmitters, an expensive and
hard to exactly realize component. Bader presented
a solution without those hard to realize transmitters
by only a partial reduction of a pole of a two-port
realized with a coil. He needed more than the minimal
number of components but only easy to realize
elements. This solution has become the preferred filters
in telephone systems. They established Bader's
Digital Object Identifier 10.1109/MCAS.2022.3189892
Date of current version: 5 September 2022
THIRD QUARTER 2022
reputation as the pioneer of, as he
called it, network synthesis. The
objective of network synthesis is
to find a realizable electrical network
from given requirements using
mathematical methods. In this
area Bader found a solution with
synthesis of electrical filters, which
is used in electrical transmission
systems for separation of information
generally transmitted in parallel.
Wilhelm Bader was not only a
pioneer of synthesis methods, but
also an enthusiastic and inspiring
academic teacher. From 1955 to
1957, he served as the principal of
the university. As the calculations for the solution are
somewhat involved, tables with sets of numerical solutions
were published, especially for the worldwide
telephone industry.
The problem of a metallic ball suspended in a magnetic
field also arose Bader's interest. The ball had only
a labile balance. Bader found that a stable balance was
reached if the transfer function of the system possesses
only poles and zeros in the left half plane. This result
was important for the endeavour of the German railway
company to build floating high-speed trains, which were
abandoned after a terrible accident.
In later years, Bader devoted to the development of
an electric method to determine zeros of a polynomial. It
consisted of a tub filled with electrolyte, the edge of which
consisted of a circle of electrodes around the tub. A finger
like electrode was searching for zeros in the electric field
in the electrolyte. However binary numbered calculators
were the final solution. Bader was an honoured member
of the commission of the DFG (Deutsche Forschungsgemeinschaft)
for computers, where also Prof. Küftmüller
was a member.
From 1955 to 1957, Bader was also a Rector (President)
of the Technical University of Stuttgart. After retirement
(continued on page 60)
IEEE CIRCUITS AND SYSTEMS MAGAZINE
51
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