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The electronic battlefield poses a dilemma for conventional radio communications, which can maximize either signal strength or noise filtering, but not both.
The electronic battlefield poses a dilemma for conventional radio communications, which can maximize either signal strength or noise filtering, but not both.
Commercial high-temperature superconductor technology promises to end this predicament. It improves the range, coverage and bandwidth of communications equipment. In some cases, it can increase reception distances by 50 percent.
Wireless carriers are using superconducting front-end filters to expand base station coverage and combat interference from the growing number of wireless services.
Like wireless telephony, battlefield radio communication suffers from out-of-range links, inadequate bandwidth, channel interference or, sometimes, intentional enemy jamming. If commanders can't hear a signal, it doesn't matter whether
they have sophisticated decision-support networks to process it.
The Defense Department's recent Quadrennial Defense Review noted that the U.S. military must develop more secure, jam-resistant data links and find ways around the current and projected bandwidth constraints.
Superconductors, invented in 1986, allow much more radio noise filtering without blocking the desired signal. But they require cryogenic cooling to conduct electricity with little resistance. High-temperature superconductors now can operate at about minus 165 degrees Celsius.
Inserted as a front end to existing antennas or radios, they are being evaluated by the Navy, the Air Force and intelligence agencies. Current units weigh about 30 pounds and take about a half-hour to cool to superconducting temperature.
Because the superconductors have negligible radio-frequency losses, they can accommodate multiple filtering stages to cut noise to as little as one part per billion at frequencies near the desired communications band. Tunable superconducting filter systems are in development.
Randy Simon is chief technology officer of Conductus Inc. of Sunnyvale, Calif. Chip Lohman, a 21-year Marine Corps veteran, is Conductus' government business development manager.
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