IEEE Spectrum: Radios With Micromachined Resonators.
It’s likely that better mechanical components, and the cognitive-radio techniques they enable, will usher in the next wave of mobile telephony by giving our cellphones access to much more spectrum. These phones will operate in multiple bands, provide greater data throughput, and minimize if not eliminate the need for wireless providers to drop our calls because traffic exceeds capacity. Consumers will love the result, even if they don’t know anything about the high-tech mechanics that may soon make it possible.
How can mechanical devices outperform electronic ones? One reason is that they generally consume no battery power. Another has to do with the quality factor of the resonating components, a quantity that physicists and engineers denote with the letter Q. The higher the Q, the more selective the resonator will be in responding only to a narrow range of frequencies.
Like any good radio receiver, the one in a cellphone requires resonators with Qs greater than 1000. Resonant electrical circuits, typically built with capacitors and inductors, have great difficulty achieving values that high. Indeed, the inductors in conventional integrated circuits are dismal, generally yielding circuits with Qs of less than 10. Vibrating mechanical resonators, on the other hand, can easily provide values in the required range.
