The story of the working group investigating the Rotterdam device is a fascinating glimpse into the rapid reverse-engineering efforts conducted by Germany during World War II. This case demonstrates the effectiveness of including the major industrial players of the time when tasked with exploiting captured enemy technology.

By consolidating the expertise and resources of various companies and research groups, the working group was able to quickly analyze the function and capabilities of the Rotterdam radar device. Through interrogations of prisoners, examination of the hardware, and collaborative investigations, the team rapidly developed an understanding of the system's navigation, bombing, and other potential applications.

The summarized meeting protocols serve as a testament to the power of mobilizing a nation's scientific and manufacturing resources when faced with the imperative of exploiting enemy technological innovations."

Working Group Rotterdam

(Arbeitsgruppe Rotterdam)

2nd Meeting / 17 March 1943

The second report, dated March 21, 1943, stated that a second Rotterdam device had been delivered since the initial capture. Further investigations revealed that the magnetron powering this device had been measured to operate at a probable wavelength of 9.15 cm. This finding was corroborated by the performance of several additional prototype models that had been built.

Statements from prisoners of war indicated that the Rotterdam device was a navigation system used by pathfinder aircraft to drop marker bombs. With a magnetron power consumption of 300-350 kW and an output power of 20-30 kW, the system's efficiency was estimated to be around 10%. The report expected that the first replicas of this device would be available within two weeks, just two months after the initial captured Rotterdam unit.

While German companies were able to produce magnetrons with a similar wavelength, these were only capable of a continuous output of 10W. Unfortunately, the report did not specify the intended applications for these lower-power tubes.

In parallel, the development of detection equipment codenamed "Naxos" was underway. An initial series of 100 Naxos detectors were being produced, with four units delivered to the test field daily. These were intended for installation in aircraft, as well as specially adapted versions for ground-based warning systems (Naxos W), submarines (Naxos-U), and homing devices (Naxos Z). Concurrently, the decision was made to commence the construction of jamming devices.

To support the development of these jammers, efforts were also focused on building measurement equipment for the centimeter wavelength range and producing insulating molding compounds for RF cables and other components.

3rd Working Group Meeting, April 8, 1943

Meeting Record, April 12, 1943

The statements from prisoners of war corroborated the industry's investigations. The function of the switch unit is now fully understood, and the significance of the bomb-release curves has been elucidated. For the first time, a display unit has been recovered, although it was badly damaged. Concerningly, it is now feared that the entire system represents only the initial stage of development, and further advancements using shorter centimeter-wave (microwave) technology with correspondingly greater resolution may be forthcoming.

All of the device's navigation and bombing-related functions have been clarified, though it remains unclear whether other applications, such as blind landings, are planned. The circuit diagrams and parts lists have been thoroughly documented, with only the display unit still requiring further development.

Additionally, the report detailed the receivers now available in the centimeter-wave range and the ongoing development of receivers operating at 4 cm and below.

A first detector device, codenamed "Stieglitz" (Eurasian Tree Sparrow), and a ground-based warning system, Naxos W, had already been tested by the Luftwaffe in the occupied western territories. The Rotterdam devices that had been monitored transmitted for several minutes at a pulse repetition frequency of 650 Hz and a rotation speed of 1.5 seconds. Conversely, a Naxos I unit set up at a different location detected a significantly higher pulse frequency of 14,000 Hz.

It was determined that the low pulse frequency and directionality of the Naxos Z series homing device's transmissions would make the task of building this device challenging to accomplish.