Alfred Lee Loomis, a millionaire and physicist who headed his own private laboratory, organized the Microwave Committee to consider these devices and look for improvements.

GEC made 12 prototype cavity magnetrons at Wembley in August 1940, and No 12 was sent to America with Bowen via the Tizard Mission, where it was shown on 19 September 1940 in Alfred Loomis’ apartment.

These usually operated at Very High Frequency (VHF) wavelengths in the electromagnetic spectrum and carried several cover names, such as Ranging and Direction Finding (RDF) in Great Britain.

In February 1940, researchers John Randall and Harry Boot at Birmingham University in Great Britain built a resonant cavity magnetron to fill this need; it was quickly placed within the highest level of secrecy.

Shortly after this breakthrough, Britain's Prime Minister Winston Churchill and President Roosevelt agreed that the two nations would pool their technical secrets and jointly develop many urgently needed warfare technologies.

On October 6, Edward George Bowen, a key developer of RDF at the Telecommunications Research Establishment (TRE) and a member of the mission, demonstrated the magnetron, producing some 15,000 watts (15 kW) of power at 3 GHz, i.e. a wavelength of 10 cm.

Ernest Lawrence was an active participant in forming the Rad Lab and personally recruited many key members of the initial staff.

In June 1941, the NDRC became part of the new Office of Scientific Research and Development (OSRD), also administered by Vannevar Bush, who reported directly to President Roosevelt.

The OSRD was given almost unlimited access to funding and resources, with the Rad Lab receiving a large share for radar research and development.

Starting in 1942, the Manhattan Project absorbed a number of the Rad Lab physicists into Los Alamos and Lawrence's facility at Berkeley.

[6] The Radiation Laboratory officially opened in November 1940, using 4,000 square feet (370 m2) of space in MIT's Building 4, and under $500,000 initial funding from the NDRC.

They had an existing hyperbolic navigation system, called GEE, but it was inadequate, in both range and accuracy, to support aircraft during bombing runs on distant targets in Europe.

[9] Following the Japanese Attack on Pearl Harbor and the entry of the U.S. into World War II, work at the Rad Lab greatly expanded.

Half of the radars deployed by the U.S. military during World War II were designed at the Rad Lab, including over 100 different microwave systems costing $1.5 billion.

Although the Rad Lab was initiated as a joint Anglo-American operation and many of its products were adopted by the British military, researchers in Great Britain* continued with the development of microwave radar and, particularly with cooperation from Canada, produced many types of new systems.

The objective was an airborne early warning and control system, providing the U.S. Navy with a surveillance capability to detect low-flying enemy aircraft at a range in excess of 100 miles (161 km).

The project was initiated at a low level in mid-1942, but with the later advent of Japanese Kamikaze threats in the Pacific Theater of Operations, the work was greatly accelerated, eventually involving 20 percent of the Rad Lab staff.

[12] As the Rad Lab started, a laboratory was set up to develop electronic countermeasures (ECM), technologies to block enemy radars and communications.

With Frederick E. Terman as director, this soon moved to the Harvard University campus (just a mile from MIT) and became the Radio Research Laboratory (RRL).

Most of the important research results of the Rad Lab were documented in a 28-volume compilation entitled the MIT Radiation Laboratory Series, edited by Louis N. Ridenour and published by McGraw-Hill between 1947 and 1953.

[13] Postwar declassification of the work at the MIT Rad Lab made available, via the Series, a quite large body of knowledge about advanced electronics.