Bringing Cognitive Radios Closer to Reality
I would rather not hazard a guess at how many radio signals are passing through my body right now, but I do know that some frequencies are passing through more than others. This is because there may be more cellphone transmissions going on than Wi-Fi or television signals at the moment, and each use different parts of the spectrum. Such a disparity between frequencies means that transmissions can become congested, even though there is still plenty of bandwidth, but researchers at MIT are working to changes that.
Cognitive radio is a 15 year old idea of a wireless device that will switch frequencies to less used channels, to improve performance. The catch is that the filters needed to switch frequencies can have multiple inefficiencies while also being large and difficult to integrate into electronics. The MIT researchers however have found a fairly elegant way around those issues by employing a specific material in a capacitor. Capacitors can be thought of as two metal plates a short distance apart, that an electric field can cross. What the researchers have done is made one of the plates out of a semiconductor, so they can switch it to a non-conducting state at will. This enables a reduction in energy loss due to the capacitor and integrates the switch needed for the filter to operate in a smaller package.
The semiconductor the researchers used is gallium nitride, which can already be found in some electronic components, so mass production can be achieved without having to greatly alter current processes.