Under the three-year contract, Boeing will deliver to Space and Naval Warfare Systems Center, San Diego, an antenna with a phased array architecture that exhibits low radar cross section and infrared signature. The program is to be managed by Boeing Phantom Works in Seattle. Phantom Works is the advanced research and development unit of The Boeing Company.

Many current shipboard antennas, particularly those required for satellite communications, use heavy, expensive pedestals for precise steering. The pedestals' heavy weight aloft can compromise the ship's stability and the large radar reflecting surfaces dominate the ship's radar cross section.

The Boeing design will be lighter in weight and have lower-life cycle costs than current shipboard antennas.

The designs will meet existing Milstar and Global Broadcast Service (GBS) satellite communication signal, gain and sensitivity requirements. The performance of the antennas will be demonstrated at sea in 2001 after installation on the research vessel RV Lauren.

The Phantom Works phased array communication antenna development program will have three stages: design, fabrication and testing of a 44-GHz active transmit array, a 20-GHz active receive array, and transmit and receive Ku-band arrays.

The program is based upon technology development activities funded by the Air Force Research Laboratory, Hanscom Air Force Base, Mass.; the Navy Space and Naval Warfare Systems Center, San Diego; NASA Lewis and Goddard Space Flight Centers, Cleveland, Ohio and Greenbelt, Md.; and by Boeing internal research and development programs.

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Under the two-year contract, Boeing will deliver an antenna with a planar, phased array architecture that exhibits low radar cross section to the Naval Undersea Warfare Center, Newport, R.I.

According to Dr. Gary Miller, Phantom Works antenna program manager, the flat, innovative design of the Boeing antenna makes it ideally suited for the unusual constraints of the submarine environment. "The compact Boeing antenna can survive the submarine environment and deploy from a submarine mast," Miller said. "In addition, it will provide submarines with high-data-rate communications while minimizing system volume requirements and radar cross section."

The contract will be executed in two phases. During the first phase, Boeing will develop antenna designs that address the highest-priority submarine satellite communications (SATCOM) bands while meeting stated goals for antenna performance, antenna compactness, ability to address submarine environmental requirements, and stealth. The design approach will leverage related phased array technology developed by Boeing for other (non-submarine) applications.

In Phase II, Boeing will fabricate and test an antenna built to one of the designs produced in Phase I. Testing during this phase will include antenna electrical performance, radar cross-section, and environmental testing.

The second objective of Phase II is to project the performance and cost aspects of this antenna technology in a system context.The program is based upon technology development activities funded by the Air Force Research Laboratory (Hanscom Air Force Base, Mass.), the Navy Space and Naval Warfare Systems Center (San Diego, Calif.), NASA's Glenn Research and Goddard Space Flight Centers (Cleveland and Greenbelt, Md., respectively) and by Boeing internal research and development programs.

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The challenge at Boeing Satellite Systems builder of nearly 40 percent of the satellites in commercial service worldwide is to remain ahead of the pack and sustain a strong, stable, growing business. "BSS has developed some unique technologies that will help the enterprise fulfill its mission of expanding the business while enabling new service opportunities for its customers," said BSS

President Randy Brinkley. "These technologies are market discriminators and give us leverage against our competition in commercial and government markets."

Phased array antennas

The challenge: Create a satellite system that can blanket an entire continent with two-way, high-speed Internet, data, voice, video, and multimedia services for consumers ranging from telecommuters to small businesses and government organizations. BSS will meet this mandate with such key enabling technologies as phased-array antennas.

An antenna beams satellite transmissions to a given point. "Phased array" refers to the antenna's ability to change the beams' direction and shape to accommodate changing user locations and service times, and to serve new customers. Beam reconfiguration on early satellite programs had to be specified before launch; phased array antennas allow beam patterns to be changed after the satellite has been put into service, enhancing the versatility of BSS satellites carrying this technology.

One BSS-built satellite system employing phased array antennas is Spaceway, which is scheduled to begin service in 2003. Spaceway, built for Hughes Network Systems, features two Boeing 702 satellites that will cover North America. Other BSS-built satellite systems using phased-array antennas include the Tracking and Data Relay Satellite System and the Wideband Gapfiller Satellite system, both government programs, as well as commercial programs like London-based ICO. "Most parts for the antenna are pioneering inventions," said Tom Fitzhugh, BSS's Spaceway downlink antenna team lead. "They represent the first generation of products that will continue to evolve."

Digital, reconfigurable payloads Satellites collect and distribute signals carrying voice, data, imagery, and other information. Spacecraft with analog signal processors receive incoming signals on one frequency, then beam them back, or downlink, to a pre-selected geographic area.

While this technology is preferred for direct-to-home television service, digital signal processing paves the way for multiple signals to be transmitted quickly and efficiently.

Digital signal processors can discriminate between incoming signals and interference, generating clearer signals and allowing smaller user antennas. In addition, onboard digital processing significantly reduces the time delay traditionally associated with communications satellites.

BSS has been developing and improving digital signal processor technologies since the late 1970s. It has evolved into one of the enterprise's core competencies in both government and commercial programs.

Phased-array antennas and digital signal processors are complementary technologies; whereas the former allow customers to change where and how signals are sent, the latter allows them to change what signals

they send. BSS satellites equipped with either of these capabilities can reconfigure their "spot beams" and frequencies on orbit to target new markets and applications. Like a flashlight, a spot beam can be aimed at an exact small area on Earth, then moved elsewhere to reach additional customers. With spot beams, available frequency spectrum can be reused multiple times."In the telecommunications business, it's difficult to project three to five years into the future, much less the 15-year life of a satellite," Brinkley said. "Digital signal processors and reconfigurable digital payload technology allow customers to adjust to changing market demands and new business cases over the life of their satellites."

Bandwidth Efficient Modulation Satellite payloads transmit data across a finite bandwidth to a ground station or consumer. But worldwide demand for satellite bandwidth is growing, and maximizing customer revenues will require next-generation communications satellites to make optimal use of it.

Boeing Satellite System's solution to making the most of this finite commodity is Bandwidth Efficient Modulation, which allows customers a choice of transmitting more data within a bandwidth or transmitting the same amount of data using less power. BSS has been developing BEM since 1994, initially focusing on analog techniques. With advances in digital signal processing, digital is the technology of choice for BEM. "This technology is fully mature and ready to be used," said Gail Taylor-Smith, BSS director of Strategic Technology. "BEM can enhance all varieties of BSS-built satellite systems and has shown the ability to transmit three to five times more information over the same bandwidth. These accomplishments allow us to offer significant increases in data capacity for next-generation government and commercial communication satellite systems."

Boeing Satellite Systems is committed to providing the world's best satellites and satellite-based systems. By continuously developing such technologies, the enterprise is achieving this vision.

Source: http://www.boeing.com/news/frontiers/archive/2002/july/i_sc.html