By John McHale
CLEVELAND - Satellite designers are attacking size, weight, and power consumption on communications payloads by using super-efficient microwave circuits built with high-temperature superconductors.
Engineers at the NASA Lewis Research Center in Cleveland and a consortium of four companies are using high-temperature superconductors to craft microwave circuits with lower conductor loss, lower noise, and wider bandwidths than microwave circuits manufactured with traditional methods.
This design approach enables satellite designers to reduce the size of many parts on communications payloads, which lowers the satellite`s overall weight and enables engineers to add fuel to the spacecraft and lengthen its operating life, says Joseph Warner, senior physicist in the communications technology division at NASA Lewis.
Making up the thin film of the superconductor are yttrium barium cuprate and dithalium dibarium calcium dicuprate (YBCO and Tl-2212), which go on top of 3-inch thin wafers of lanthanum aluminate made at E. I. Dupont Inc. in Wilmington, Del.
Using high-temperature superconductor thin-film technology can help designers reduce payload weight by as much as 17 kilograms, which can add four to six months to the life of the spacecraft, as well as reduce launch costs, says Kul Bhafin, branch chief in the communications technology division at NASA Lewis.
The use of the previous technology, a conventional dielectric resonator, in a satellite has a total mass of 26.2 kilograms, while a high temperature superconductor has a total mass of 9.2 kilograms, according to a NASA statement.
The other enabling technology is the cryo-cooler, designed by experts at Lockheed Martin Missiles and Space Co. in Palo Alto, Calif., Bhafin says.
The engineers at Lockheed used the pulse-tube cryo-cooler over the earlier standard sterling cycle device because it uses fewer moving parts, therefore saving weight and power, says Ted Nast, project leader for advanced technology at Lockheed Martin Missiles and Space. The device cools the superconductor to 77 Kelvin.
The other two companies in the agreement are COM DEV International Ltd. in Cambridge, Ontario, whose officials are providing the microwave components and subsystems development; and engineers at Lockheed Martin Communications and Research Center in Princeton, N.J., who are testing the integrated subsystem for space worthiness.
Funding comes from the Technology Reinvestment Program of the U.S. Defense Applied Research Project Agency in Arlington, Va.
