Let me see if I can explain this better than most of the articles that I’ve been reading on this subject.
It’s a means of wireless data transmission called Near Field Magnetic Communication. in regular wireless communication, standard RF is sent and received by electromagnetic induction between two wires (antennas) over a distance. In NFMC, its just magnetic induction between two magnets over a distance. The same modes of communication, frequency, phase, or amplitude modulation can be used.
Here’s what makes this desirable for certain applications; NFMC attenuates, that is the signal looses strength, much more rapidly over distance. RF attenuation in the atmosphere is a square inverse proportion to power. NFMC attenuation is also an inverse proportion to power, but to a factor of 6 rather than 2. What this means is that in close, the signal is quite strong, even at low power, but drops off very rapidly—so rapidly in fact, it’s effectively a bubble, beyond which it cannot be picked up or detected.
Obviously we don’t want to try to use this for long distance communications. But there are uses for this that would be far superior to wired or RF wireless application. Consider the Land Warrior system. Land Warrior is a computer, a GPS, a radio, a heads-up display and a rifle mounted camera all worn by individual troops. Currently, these pieces are either connected by wire (up the neck to the helmet for example, or across the arm to the rifle—you can imagine the potential problems here) or wireless, as, I believe is the link between processor and GPS.
The RF link is detectable at some distance, albeit a short one, its a risk that doesn’t have to be taken with NFMC.
Essentially, a bubble, roughly the reach of the individual soldier, is created inside which these elements can all communicate with each other without any physical, or detectable connection.
Another drawback of RF wireless links is that of “body shadow.” The human body is an efficient absorber of RF energy, which means that an RF antenna has a limited number of positions in which it can be placed in order to maintain good signal with the other components. Unpredicted circumstances could result in link loss because of odd body position or even simply being in close proximity to another person. The human body, however, is transparent to the magnetic field. The magnetic “antennae” for an NFMC system could be placed anywhere.
The private sector is already using this for cell phone hands-free devices.