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A Hundred Billion Antenna Reconfigurations

Antenna_image.jpgCavendish Kinetics recently made an announcement regarding their ongoing reliability testing for their MEMS-based antenna-tuning technology.

We’ve talked about this tuning concept before (albeit with a different name); the short version is that, with all of the different bands that cell phones need to access, it becomes difficult to optimize the antenna for all of them in the limited space available. So the idea is that you have a capacitor array switched by MEMS elements, and you can then change up your filter with each band to optimize accordingly.

We also looked in more depth at Cavendish Kinetics’ particular approach before, including a description of work they’ve done to limit the range of switching capacitor plates to keep them from over-traveling or slamming too hard against stops.

But, such assurances aside, the question phone makers have remains: how reliable are those MEMS elements? How many times can you switch them before they fail?

Well, according to Cavendish Kinetics, a lot. Like, 100 billion cycles and counting.

And who needs that many cycles? Well, no one, actually, according to them. But, hey, when you’re on a roll, might as well keep it going to put any lingering doubts to rest.

In my mind, I make some comparison to a gyroscope, which has to be in constant motion. Where there is literally a mechanical member moving (as opposed to techniques involving internal resonances), you can add up those movements pretty quickly. Billions aren’t hard to attain. Even if the frequency was a slow 1 kHz, you’d hit a hundred billion cycles in just over 3 years.

But here’s the difference: with the capacitor array, the elements move only when you change configuration. While in use in a particular configuration, the switches are static. If you changed configurations every second, then in three years you’d get roughly (just under) a billion switching events. Which means it would take running the system that aggressively for on the order of 300 years to get to a hundred billion cycles.

I’m thinking the battery would probably wear out first. (And it suggests that their test runs somewhat faster than 1 Hz…)

You can read more about this in their announcement.

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