A Receiver Array to Reduce the Effects of Misalignment in Magneto-Inductive Communication

In this paper, a magneto-inductive (MI) communication link is designed to cross the air-water interface for a transmitter that is 20 meters below the surface. Simulations are used to identify the geometry of the coils, as well as an optimal transmit frequency on the order of 1 kHz, constrained on a relatively low transmit current of one A RMS. At this frequency, it is shown that the capacity is equal to 5,820 bps, due to the extremely high SNR, over 50 dB. The performance varies significantly with the distance, because the MI link operates in the near field and the bandwidth is reduced because of the conductivity of seawater. The use of an array is demonstrated to improve the SNR with and without misalignment, and a wideband sensor array is proposed to develop a low-noise link receiver. In fact, a 3-element coil array is proposed, and it is expected that the link will be able to achieve an SNR well above 0 dB for a depth of 20 meters.