Karl Ferdinand Braun (German: [ˈfɛʁdinant ˈbʁaʊ̯n]; 6 June 1850 – 20 April 1918) was a German scientist who shared the 1909 Nobel Prize in Physics with Guglielmo Marconi for their work on radio technology. His two-circuit system helped make long-distance radio communication and modern telecommunications possible. In 1905, he invented the phased array antenna, which later led to the development of radar, smart antennas, and MIMO. In 1897, Braun built the first cathode-ray tube, which helped create television. In 1874, he made the first semiconductor diode, which helped start the development of electronics and electronic engineering.

Braun was a co-founder of Telefunken, one of the first companies to work on communications and television. He was called the "father of television" (shared with inventors like Paul Nipkow), the "great-grandfather of every semiconductor ever manufactured," and a co-father of radiotelegraphy, together with Marconi, laying the foundation for all modern wireless systems.

Biography

Karl Ferdinand Braun was born on 6 June 1850 in Fulda, Hesse-Kassel. In 1868, he began studying physics, chemistry, and mathematics at the University of Marburg. The next year, he moved to the University of Berlin and worked as an assistant to Heinrich Magnus. After Magnus died in 1870, Braun continued his studies with Georg Quincke. In 1872, he earned his Ph.D. with a thesis about vibrating strings, and later joined Quincke at the University of Würzburg as an assistant.

In 1874, Braun accepted a teaching job at the Thomasschule in Leipzig. In 1876, he returned to the University of Marburg as an Extraordinary Professor of Theoretical Physics. In 1880, he took a similar position at the University of Strassburg. In 1883, he became a Professor of Physics at the Karlsruhe Institute of Technology. In 1885, he was invited to the University of Tübingen. In 1895, he returned to Strassburg as Principal of the Physics Institute.

In 1897, Braun joined the group of scientists working on wireless communication. His key contributions to radio included using a closed tuned circuit in the transmitter, separating the transmitter from the antenna with inductive coupling, and later using crystals to receive signals. Around 1898, he invented a crystal detector. In 1898, he focused fully on solving problems in wireless telegraphy. He wrote many articles on wireless topics and contributed to scientific journals like The Electrician. In 1899

Inventions and discoveries

In 1874, Braun discovered that certain materials conduct electricity unevenly in different directions. This finding became the basis for the point-contact rectifier, a device that allows electricity to flow more easily in one direction than the other. This property is essential for diodes, which are used in many electronic devices.

Braun's research with semiconductors led to the creation of the first point-contact diode. This device was one of the earliest practical uses of semiconducting materials. It enabled the conversion of alternating current into direct current, a key step in developing modern semiconductor technology like diodes and transistors.

Braun's work helped lay the foundation for the electronics industry. His discoveries were important in the early development of electronic devices and the semiconductor industry.

Braun is also known for inventing the cathode-ray tube (CRT), often called the "Braun tube." The CRT is a vacuum tube that uses an electron beam to create images on a screen. The first version, made in 1897, had limitations, such as a cold cathode and a weak vacuum. It required a very high voltage to produce visible images and had issues with controlling the beam's direction.

Despite these challenges, the CRT's potential was quickly recognized. Improvements included adding a heated cathode, a Wehnelt cylinder, and better vacuum technology. The CRT was used in oscilloscopes and early electronic televisions, even though Braun did not think it was suitable for television.

The CRT became a key component in early electronic televisions. It was used in televisions, computers, and other screens until the introduction of LCD technology in the late 20th century. The term "Braun tube" is still used in some countries to describe the CRT.

After inventing the CRT, Braun worked on wireless telegraphy. Early radio receivers relied on coherer devices, which were unreliable. Braun replaced coherers with crystal detectors, which improved receiver sensitivity. Later, electron tubes replaced crystal detectors, though some simple receivers continued to use germanium diodes.

In 1898, Braun's radio technology was commercialized through a partnership with Ludwig Stollwerck, a chocolate manufacturer. This led to the creation of Telefunken AG, a company that established the first global communication network. Telefunken later became the first company to sell televisions with CRTs in Germany in 1934.

Braun also improved radio transmission by separating resonant and antenna circuits. This change allowed for more efficient energy transfer. By 1898, radio signals could be sent over much longer distances. In 1900, a successful radio link was established between Cuxhaven and Helgoland, a distance of 62 kilometers.

Braun worked to replace spark-gap transmitters with AC generators that produced steady oscillations. However, he could not create a feedback loop using electron tubes at the time.

Braun collaborated with others to develop mobile wireless telegraphy systems for military use. These systems used two horse-drawn wagons, one for equipment and the other for supplies. This design allowed the system to operate even if one wagon was separated.

Braun also studied directional radio, focusing on aligning transmitting and receiving antennas for better performance. He was among the first to calculate how to direct radio waves more effectively.

Braun is also credited with inventing the pointer electroscope, a device named after him.

Commemoration

In 1987, the Society for Information Display established the Karl Ferdinand Braun Prize. This award is given to someone who has made an outstanding technical achievement in display technology.

Patents

• U.S. Patent 0,750,429, Sending Electrical Signals Without Wires Across Surfaces
• U.S. Patent 0,763,345, A Way to Change and Set Electrical Circuits