Self-Adjusting Satellite Antennas.

Researchers at Ohio State University, Columbus, have taken a big step toward developing adjustable antennas for satellite communications. Such an antenna could change the shape of its reflector while in orbit to improve signal quality. It also could replace several traditional antennas by delivering a variety of signals for cellular phones, pagers, and global positioning systems.

Scientists previously had found that adjustable reflectors made of plastic were light enough for use in space, but too flexible to afford good shape control. Gregory Washington, assistant professor of mechanical engineering, and Hwan-Sik Yoon, a graduate student, have proven through computer simulations that thin piezoceramic patches spaced around the back of a reflector will reinforce the plastic while controlling its shape.

A piezoceramic material is a ceramic that changes shape when a voltage is applied to it, or releases a voltage when its shape is changed manually. Researchers sometimes call these "smart" materials. "When we attach this piezoceramic material to another surface and it expands, the surface bends. When it contracts, the surface bends the other way. With that movement, we're able to change the overall shape of a structure. In this case, the shape change alters the properties of the reflector or antenna itself," Washington explains.

Satellites normally must move the entire mechanism beneath an antenna to change its direction. "It's as if our eyes could only stare straight forward--to see other directions, we'd have...