Date: Apr 11, 2014 Author: John Keller Source: Military & Aerospace Electronics (
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Military systems designers today are obsessed with shrinking component size, weight, and power (SWaP). Connector and cable manufacturers-no small contributor to SWaP on military vehicles-are stepping up to the challenge in a variety of approaches.
The drive toward shrinking SWaP for unmanned vehicles, wearable computers and displays, networked weapon sights, and many other applications of embedded electronics is playing into the hands of companies that design small electronic parts called micro and nano connectors.
Not only does the shrinking voltages of modern microprocessors and other integrated circuits lend itself to small interconnects, but micro and nano connectors can be inherently rugged, explains Bob Stanton, director of technology at Omnetics Connector Corp. in Minneapolis.
This photo shows a ruggedized, multiple protocol-enabled, electrically pluggable active optical cable from Zephyr Photonics.
This photo shows a ruggedized, multiple protocol-enabled, electrically pluggable active optical cable from Zephyr Photonics.
"Everything has to be smaller and able to handle this new digital lower-voltage technology," Stanton says. "The rules of silicon run into the connectors, and that allows less voltage, smaller connectors, smaller wires, and tighter spacing."
Small size, however, in itself is not a substitute for rugged connectors in today's military applications. "We have UAVs [unmanned aerial vehicles] that are two feet wide at most, and have to take lots of shock and vibration," Stanton says. "Sometimes they even have to crash land. We need high signal integrity through real rugged applications. At the same time, designers want smaller and lighter connectors to fit into this little vehicle or product."
One big advantage of smaller connectors in high shock-and-vibration environments is their physical mass. "The mass is lower, and it handles higher forces," Stanton says. There are other challenges, however. "The plating on the pins must be exceptionally good," he adds. Typically Omnetics engineers use a mix of nickel and gold-nickel for hardness and gold for electrical conductivity.
Other companies are taking a different approach to attack SWaP issues with cables and connectors. One approach involves substituting optical fiber for copper cable, which not only reduces weight and mass, but also resists the effects of electro-magnetic interference (EMI).
From a design standpoint for military applications, fiber and fiber connectors have represented maintenance and reliability headaches. One bit of dirt in an optical connector can compromise performance. "You're in a dirty environment with people who don't know much about fiber," says Tim McAllister, vice president of business development at Zephyr Photonics Inc. in Zephyr Cove, Nev. So Zephyr's approach is to combine electrical connectors, with which military technicians and systems integrators are familiar, and run optical fiber between.
The result is a rugged electrically pluggable active optical cable.
The connectors are electrical and in familiar form factors. The cables convert the electrical signal to optical just behind the connector, and re-convert the signal back to electrical at the other end. An added benefit to using fiber is increased bandwidth.
"For the sensor folks, in particular, bandwidth over distance is a big application," McAllister says. "It will be the upgrade path for many sensors in the next five to seven years."
