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| | Personal Area Networks: Near-field intrabody communication |
 | | Far-field (radio) communication is more susceptible to eavesdropping and interference than near-field communication due to the former's propagation properties: an isotropic radio transmitter propagates energy with a signal strength that decreases with distance squared, whereas near-field strength decreases with distance cubed. |
 | | A communication network is judged primarily by channel capacity, with a theoretical limit defined by the Hartley-Shannon law [5] C = Blog(1 + S/N), where C is channel capacity in bits/second, B is bandwidth, S is signal, and N is noise. |
 | | When the woman and man depicted in the figure are in close proximity, particularly when they shake hands, an electric circuit is completed, allowing picoamp signals to pass from the transmitter through her body, to his body, to the receiver by his foot, and back through the earth ground. |
| www.research.ibm.com /journal/sj/353/sectione/zimmerman.html (3131 words) |
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