During World War II, the use of radar technology in aircraft presented both strategic advantages and risks for the Allied forces. This led to significant discussions and concerns about its deployment.

Strategic Considerations:

Allied commanders had to weigh the tactical advantages of radar-equipped aircraft against the risk of the technology falling into enemy hands if an aircraft was shot down over enemy territory. However, Allied strategists believed that even if the Germans captured radar equipment, it would take them considerable time to analyze, understand, and reproduce the technology effectively. They estimated this time would be longer than the expected duration of the war.

Ongoing Technological Race:

Both sides were constantly improving their radar technology throughout the war. By the time the Germans might have reverse-engineered captured equipment, it could already be outdated. The benefits of radar for navigation, target acquisition, and defensive operations were so significant that they outweighed the potential risks.

The Rotterdam Incident:

A significant event occurred on February 2, 1943, when a Pathfinder aircraft equipped with advanced radar was shot down near Rotterdam. The radar's magnetron, made of a copper block due to its high output power, was recovered by German forces. The removed parts from the downed aircraft, were brought to Berlin, and studied in laboratories of the Telefunken company. As soon as February 22, 1943 a working group was formed to analyze and replicate the device and create the necessary countermeasures against the ‘Rotterdam’ procedure. 

German Discoveries:

The working group discovered that the magnetron, an invention abandoned in Germany due to unstable frequencies, allowed for shorter wavelengths of 3cm (3.3 GHz) instead of the 54cm (560 MHz) used in the German Würzburg device for detecting airplanes. This technology also allowed for the detection of ground structures, useful for navigation and identifying targets for night and all-weather bombing. However, the war ended before Germany could implement this technology in their own planes.

Legal Implications:

The knowledge gained from these devices became a matter of patent law consideration. The German Supreme Court did not consider this knowledge to be "publicly available" in a patent law sense, despite the potentially large number of people involved in the working group. This decision was based on several factors:

Consequently, the use of the recovered and replicated radar display devices was not considered to have been "publicly known" in a way that would invalidate the patent, highlighting the complex intersection of wartime technological advancements and intellectual property law.

The contested patent was concerned in particular with the display unit used to show the ground reliefs. The guiding principle of the decision is therefore:

Viewing devices for radar surveillance systems, which were recovered from shot down or crashed aircraft during the war or were reverse-engineered in Germany, did not become publicly known as a result of being discussed in a working group set up specifically for this purpose, which also included representatives from individual companies in the electrical industry.

last time reviewed: 11/04/2025 gs