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

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

, was an 800-person secret research laboratory during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. Under the U.S. Office of Scientific Research and Development (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 31 ...

(Rad Lab) at MIT, and set up to develop

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

to enemy radars and communications, as well as electronic counter-countermeasures (ECCM) to circumvent enemy ECM. The RRL was directed by Frederick E. Terman 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 the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but livestock can eat it. In agri ...

, 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), 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 back to the source. ...

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 radars. 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 that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz. They are us ...

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