ITT touts GaAs MMICs for active-aperture EW antennas

CLIFTON, N.J. - Electronic warfare systems designers at ITT Avionics are touting their broadband active-aperture antennas as less expensive and more efficient alternatives to mechanically scanned antennas.

By John McHale

CLIFTON, N.J. - Electronic warfare systems designers at ITT Avionics are touting their broadband active-aperture antennas as less expensive and more efficient alternatives to mechanically scanned antennas.

The engineers at ITT Avionics, an operating unit of ITT Industries Inc. in Clifton, N.J., array Gallium arsenide Monolithic Microwave Integrated Circuit (MMIC) chips in modules behind the antenna face to enable rapid beam scanning and high reliability.

"It is faster and more flexible than mechanical devices," says Ron Schineller, manager of microwave design at ITT Avionics. "These chips are a major step in reducing the size and cost of future electronic warfare systems," Schineller says.

The high power and efficiency, functional integration, and low manufacturing costs of the new MMICs make such electronically scanned antennas practical and affordable, he says.

Experts fabricate the chips at ITT GaAsTEK, an ITT Defense and Electronics gallium arsenide foundry, in McLean, Va., using a multi-function self-aligned gate (MSAG) process.

The MSAG process attacks production costs through high yields, Schineller says. MSAG also provides for a high level of integration on a chip by packaging high-power and signal circuitry on the same chip, he adds.

Easing chip design was the Taguchi method, a statistical process that reduces the number of possible designs to between eight and 16, and eliminates faulty data quickly, Schineller explains.

ITT antenna engineers are also using a design tool from Sonnet Software in Liverpool, N.Y., Schineller says.

The advanced MMICs include 4-Watt and 8-Watt high-power amplifier chips more than twice the power of earlier devices over a 6-to-18-GHz band and operating with power-added efficiencies approaching 40 percent, ITT officials say.

The device also uses a transmit/receive (T/R) device that combines all the functions of a traditional multichip T/R module requiring six to eight separate MMIC chips.

ITT Avionics won a contract in 1995 under the DARPA-sponsored Microwave and Analog Front-end Technology (MAFET) Thrust 2 program. Officials of DARPA, which stands for Defense Advanced Research Projects Agency in Arlington, Va., are pursuing MAFET to develop advanced broadband MMIC devices.

ITT experts are delivering their developmental chips and multichip assemblies to the Naval Research Laboratory in Washington for evaluation. The ITT antenna is for shipboard applications and possibly for the future Joint Strike Fighter.

Protective packaging and the inherent resistance of gallium arsenide to naturally occurring radiation will enable the chips to perform well in high altitudes, Schineller explains.

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