In this letter, a novel two-coil magnetic communication method based on magnetic resonant coupling and frequency divarication is proposed. The half-power decay is employed to derive the boundary condition of double 3-dB bandwidths. Moreover, the expressions of load power, power ratio, andcommunication capacity are deduced based on the mutual inductance theory.
The theory proves that there exists one common peak value for the bandwidth and communication capacity. Also, the expression of peak value of the maximum capacity is derived using the boundary condition. The experimental results demonstrate that the proposed magnetic communication method has a maximum bandwidth and communication capacity at a wide frequency range, especially at low frequency.