A Cell-Phone Tower with Focus

When you talk on a cellular phone, you’re sharing radio frequencies with everyone else within a three-kilometer radius of the nearest base station. Congestion can lead to static, dropped calls, and slow downloads. In the basement of Nokia Research Center in Helsinki, Finland, Nokia has forged a new kind of antenna that focuses signals where most needed and could triple network capacity.

A traditional cell-phone tower works like a lawn sprinkler that radiates in all directions. Nokia’s antenna works like a hose. It’s fashioned out of copper strips, each about eight centimeters wide, welded together into a surface covering about one square meter. A case behind the copper sheet contains sophisticated amplifiers and digital signal-processing circuits that steer as many as eight separate beams in different directions, depending on demand. “The basic idea is that in a crowded area, you want to give the maximum signal to the appropriate person rather than wasting the energy by spreading it out over a broader volume,” explains Greg Hindman, presi-dent and cofounder of Torrance, CA-based Nearfield Systems, which builds testing and measurement systems.

While the antenna could theoretically multiply network capacity by a factor of eight, geographical obstacles and other sources of interference mean it actually doubles or triples capacity, says Hannu Kauppinen, senior research manager for radio technologies at the research center.