Raytheon, EL SEGUNDO: A radar antenna the length of a football field that would weigh less than the 22 players in action on it is in development by Raytheon Company under terms of an $8 million contract associated with the Integrated Sensor is Structure or ISIS program from the Defense Advanced Research Projects Agency (DARPA).
The active electronically scanned array (AESA) antenna would be bonded to the hull of an unmanned airship 150 to 300 meters (164 to 328 yards) in length that could hover for long periods above the jet stream at altitudes of 65,000 to 70,000 feet. The antenna would transmit on UHF and X-band. Raytheon Space and Airborne Systems (SAS) is a leader in AESA technology, which uses no moving parts to scan at nearly the speed of light.
“DARPA wants to be able to look for airborne and ground-based targets and to communicate directly with the battlefield from a single antenna,” said Michael Wechsberg, director of radio frequency systems programs for the Advanced Concepts and Technology group of SAS.
The low-power density radar would derive its extraordinary sensitivity from an extremely large aperture that would occupy much of the surface of the blimp-like airship.
“The mission is to develop an inordinately sensitive and lightweight sensor that can be integrated into the structure of an airship, which could remain essentially motionless over an area for a long time,” Wechsberg said. “That would let us see targets moving very slowly from a platform that would be difficult to find, let alone to knock down.”
Developing the lightweight radar antenna technology is only part of the assignment. SAS is also charged with devising a means to bond the radar to the hull or other structure of the airship to save weight.
“Using the hull as the support structure for the antenna eliminates thousands of pounds that would ordinarily be needed to provide and maintain a consistent shape for the array,” Wechsberg said. “A much larger antenna, therefore, could be carried. The program envisions the largest X-band antenna ever built.”
Although it would contain “millions of electronic components,” the thickness of the antenna as envisioned by Raytheon would be about one centimeter (0.4 inch). Only when bonded to the hull of the airship would the array be stiff enough to behave properly as an antenna.
The main challenge for the bonding technology is a hostile environment.
Bonding agents must be able to withstand ambient temperatures of -80 degrees Celsius (-112 degrees Fahrenheit). The agents also must be able to accommodate differences in thermal properties between the antenna material and that of the hull. These properties would vary broadly.
“So we need to come up with a way that in cyclical extremes of temperature will keep everything from coming apart,” Wechsberg said.
Raytheon Space and Airborne Systems (SAS) is the leading provider of sensor systems giving military forces the most accurate and timely information available for the network-centric battlefield. With 2005 revenues of $4.2 billion and 13,000 employees, SAS is headquartered in El Segundo. Additional facilities are in Goleta, Calif.; Forest, Miss.; Dallas, McKinney and Plano, Texas; and several international locations.
Raytheon Company, with 2005 sales of $22 billion, is an industry leader in defense and government electronics, space, information technology, technical services and special-mission aircraft. Headquartered in Waltham, Mass., Raytheon employs 80,000 people worldwide.
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