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1959 - operation of a new high-power experimental search radar on Boston Hill in North Andover, Massachusetts


E&MP 103.028

Radar - High Power

February 2, 1959

A new experimental high-power radar, designed by the Lincoln Laboratory of the Massachusetts Institute of Technology, recently went into operation at Lincoln's Boston Hill site, North Andover, Massachusetts.

Lincoln Laboratory of the Massachusetts Institute of Technology has completed the construction of and is now operating a new high-power experimental search radar on Boston Hill in North Andover, Massachusetts.

This radar is the direct result of experimental work on a less powerful installation at Jughandle Hill, Bath, Maine, which has now become part of the Experimental Sector of the SAGE Air Defense System. Boston Hill will be used by Lincoln Laboratory to test new high-power radar components and circuitry developments that are being designed for radars of the future.

Lincoln Laboratory is engaged in electronic research on new problems of air defense and is supported by the Army, Navy, and Air Force. Lincoln's triservice contract is administered by the Air Research and Development Command of the Air Force through the Air Force Cambridge Research Center in Bedford, Massachusetts.

Even though the antenna assembly weighs more than 50 tons, it can be rotated at speeds up to 5 RPM in winds of 60 MPH and still maintain an accuracy of less than one-tenth of a degree. The reflector measures 120 feet wide by 30 feet high - 50 per cent larger than the ext largest of its type in operation.

In order to assure long life with continuing accuracy for such a large antenna, extensive effort was devoted to the design and fabrication of the bearing and structure on which the antenna is mounted.

The 4-point-contact azimuth bearing is the largest integral gear and ball bearing yet installed, 13 1/2 feet in diameter, with 110 3-inch diameter balls matched to 0.0001 inch - 1/30th of the thickness of a human hair! The bearing problem was so complex that its solution forced the state of the art to advance considerably and the momentum imparted promises still further progress.

Unlike most radars, the Boston Hill antenna is mounted on a heavily reinforced concrete tower that houses the transmitter, receiver, and the ancillary equipments [sic], a workshop, and offices. The tower construction provides the very rigid platform necessary for the high degree of accuracy of the antenna.

The output or power tube of the transmitter is a ten foot klystron that was specifically developed under Lincoln Laboratory sponsorship for use in this radar. Transmitter energy is developed in the form of recurring pulses, each of which lasts for a few millionths of a second. This energy can be directed into space by the antenna or, for test purposes, into a dummy load.

The receiver is sensitive enough when combined with the high power of the transmitter, to detect a small plane several hundred miles away. To protect the receiver from damage by the high power of the transmitted pulse, a unique tube filled with pure argon gas is used. The gas ionizes when the pulse strikes it and prevents all but about one-millionth of the energy from passing to the receiver.

In order to provide a platform stable enough to permit the required positional accuracy of the antenna, the walls of the tower are of reinforced concrete 14 inches thick. The tower is 82 feet high, 36 feet square, and has six reinforced concrete floors which increase the torsional rigidity of the tower and provide space for the equipment.


1959 - operation of a new high-power experimental search radar on Boston Hill in North Andover, Massachusetts

Original Caption by Science Service
©  James H. Gilman, Jr. - Massachusetts Institute of Technology

National Museum of American History


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