Impedance Matching Method for Magnetic Resonance Coupling Human Body Communication

The impedance matching is the key to determine the communication quality in wireless communication field of magnetic resonance coupling human body communication. The human body impedance easily affects the resonant frequency between the communication coils, resulting in serious signal attenuation. This paper proposes an impedance matching method based on dual adjustable capacitors: series resistors are used to adjust the coil bandwidth, while dual adjustable capacitors are used to tune the resonant frequency to the preset resonant frequency and achieve conjugate matching. Using a vector network analyzer to experiment with five volunteers for dual-arm magnetic resonance coupling communication. The experimental results show that the path loss result obtained by applying adjustable impedance matching is 10.88dB lower than that of the single capacitor matching and 7.42dB lower than that of the dual capacitor matching when the distance is 60cm at 13.56MHz. This method solves the issue of impedance mismatch due to the parasitic capacitance of the human body, which provides an effective method for transmission of magnetic resonance coupling human body communication.