Improving performance of wireless communications

Researchers at the University of Missouri-Rolla (UMR) in the US and Motorola's Advanced Technology Center are developing three-dimensional switches and tiny fuel cells to improve the reception quality and extend the operating time for wireless communications and other wireless sensing devices.

"We are trying to make better switches, called Meso-MEMS, for wireless technology," says Dr Matthew O'Keefe, associate professor of metallurgical engineering and one of the leaders of this research project. The use of Meso-MEMS (MEMS stands for micro-electro-mechanical systems) as switches will not only improve reception quality, but will save energy.

"The basic switch technology gives you lower electrical loss and a higher quality signal," says O'Keefe. The switch would enable a mobile phone, for example, to be used in any geographic location by simply changing its frequency operation band. Recent tests have shown this approach is an improvement over current technology. "This system will actually enhance the consumer's mobile phone performance by providing a cleaner, stronger signal with less static," says O'Keefe.

The Meso-MEMS switches work much like a light switch. A Meso-MEMS switch is either on or off, unlike the current solid-state technology, which is on at some level all the time. One significant advantage to using this switch is that, because it does turn completely off, it saves energy.

Energy savings are also realised with current MEMS switches made of silicon, but silicon RF MEMS switches are relatively expensive, O'Keefe says. The Motorola/UMR team has discovered that alternative polymer and metal materials work just as well as silicon, and for a much lower price. In the next phase of the program the rese

archers will also be developing tiny fuel cells to power these wireless devices. The fuel cells would provide power for these products longer than traditional batteries in such wireless devices as mobile phones.

"The military could conceivably put a sensor out in the desert and leave and it would be capable of sending information for an extended period of time," says O'Keefe. Unlike batteries, however, they do not run down or require electrical recharging.