Thermodynamic Signal-to-Noise and Channel Capacity Limits of Magnetic Induction Sensors and Communication Systems

Magnetic communication systems are typically used when the medium contains matter, or when short-range communication is of interest. Previous works have disregarded impediments to transmission performance due to skin and proximity effects and radiation resistance, although such effects may be significant. This paper addresses these effects and proposes improved upper bounds on the signal-to-noise ratio (SNR) and channel capacity. It is shown that the performance of magnetic communication systems is limited by skin and proximity effects at medium frequencies and by radiation resistance at high frequencies. A conclusion is that the sensitivity of magnetic induction sensors cannot be made arbitrarily high, since the noise associated with radiation resistance increases substantially in large coils. Another conclusion is that the potential SNR of any magnetic structure peaks at a particular frequency.