The Radio Research Laboratory (RRL), located on the campus of

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

, was an 800-person secret research laboratory during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. Under the U.S.

Office of Scientific Research and Development The Office of Scientific Research and Development (OSRD) was an agency of the United States federal government created to coordinate scientific research for military purposes during World War II. Arrangements were made for its creation during May ...

(OSRD), it was a spinoff of the

Radiation Laboratory The Radiation Laboratory, commonly called the Rad Lab, was a microwave and radar research laboratory located at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts. It was first created in October 1940 and operated until 3 ...

(Rad Lab) at MIT and set up to develop

electronic countermeasures An electronic countermeasure (ECM) is an electrical or electronic device designed to countermeasure, trick or deceive radar, sonar, or other detection systems, like infrared (IR) or lasers. It may be used both offensively and defensively to deny ...

to enemy radars and communications, as well as

electronic counter-countermeasures Electronic counter-countermeasures (ECCM) is a part of electronic warfare which includes a variety of practices which attempt to reduce or eliminate the effect of electronic countermeasures (ECM) on electronic sensors aboard vehicles, ships and a ...

(ECCM) to circumvent enemy ECM. The RRL was directed by

Frederick E. Terman Frederick Emmons Terman (; June 7, 1900 – December 19, 1982) was an American professor and academic administrator. He was the dean of the school of engineering from 1944 to 1958 and provost from 1955 to 1965 at Stanford University. He is widely ...

and operated between 1942 and 1946. The RRL was engaged in both analysis and hardware development. They made significant contributions to the basic understanding of methods, theories, and circuits at very-high and ultra-high frequencies for radio systems, particularly in signals intelligence gear and statistical communications techniques. However, unlike the Rad Lab, the RRL never released significant details on its accomplishments; ECM and ECCM have always been closely guarded secrets by all nations. The RRL conducted considerable work on

chaff Chaff (; ) is dry, scale-like plant material such as the protective seed casings of cereal grains, the scale-like parts of flowers, or finely chopped straw. Chaff cannot be digested by humans, but it may be fed to livestock, ploughed into soil ...

, light-weight aluminum strips dropped in clouds from aircraft to confuse enemy radars. Fred L. Whipple, an astronomer, made detailed analytical studies of this and devised a formula giving

radar cross-section Radar cross-section (RCS), denoted σ, also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. An object reflects a limited amount of radar energy b ...

at a given wavelength per kilogram of chaff. An example of RRL hardware development was Tuba (aka 'Project Tuba'), a giant ECM system generating continuous 80-kW signals in the range of 300-600 MHz to jam German

Lichtenstein radar The Lichtenstein radar was among the earliest airborne radars available to the Luftwaffe in World War II and the first one used exclusively for air interception. Developed by Telefunken, it was available in at least four major revisions, cal ...

s. The power tube (called Resnatron) for Tuba was developed at the RRL by David H. Shone and Lauritsen C. Marshall. Tuba used a

horn antenna A horn antenna or microwave horn is an antenna (radio), antenna that consists of a flaring metal waveguide shaped like a horn (acoustic), horn to direct radio waves in a beam. Horns are widely used as antennas at Ultrahigh frequency, UHF and m ...

built of mesh wire 150 feet long and driven through 22- by 6- inch

waveguides A waveguide is a structure that guides waves by restricting the transmission of energy to one direction. Common types of waveguides include acoustic waveguides which direct sound, optical waveguides which direct light, and radio-frequency wav ...

, possibly the largest ever built. Tuba was placed in operation in mid-1944 on the south coast of England. The radiated energy was such that it lit fluorescent bulbs a mile away and jammed radars throughout Europe. The RRL staff did document some of the general theory that they developed. After the war, this was released in a two-volume publication ''Very High-Frequency Techniques'', edited by Herbert J. Reich (McGraw-Hill, 1947).

References

* Louis Brown, ''A Radar History of World War II'', Inst. of Physics Publishing, p. 293, 1999 * Steve Blank, Google Tech Talk: https://www.youtube.com/watch?v=hFSPHfZQpIQ * Raymond C. Watson Jr.; ''Radar Origins Worldwide'', Trafford Publishing, pp. 203–205, 2009
United States. Radio Research Laboratory, Harvard University. Records of the Radio Research Laboratory : an inventory
Harvard University Archives Harvard University University and college laboratories in the United States Radiation Radar {{science-org-stub