A Channel Gain Measurement Method for Magnetic Resonance Human Body Communication

Magnetic Resonance Coupled Human Body Communication (MR-HBC) is a promising human communication method with high efficiency and stability. Designing devices that utilize MR-HBC for communication requires accurate channel transmission characteristics for effective communication. However, MR-HBC has difficulty obtaining reliable channel gains. Due to the existence of an additional return path caused by parasitic capacitance during channel gain measurements, there are significant differences in the results of different measurement methods, and the measured channel gain does not necessarily correspond to the actual channel gain. In this regard, this paper proposes a method that can accurately measure the actual channel gain of MR-HBC. By modeling the electrical connection during the measurement of the measuring instrument, this paper shows that the additional return path between the transmitter and receiver in the experimental measurement is the reason for the discrepancy between the channel gain measurement results and the actual ones. Proposed that a balun device should be added to suppress the additional return path during the MR-HBC channel gain measurement in order to measure the realistic channel gain, and this is verified by experiments. The results show that before adding the balun, the MR-HBC channel gain measurements of different measurement methods show significant differences (maximum difference of 20.4 dB). When the additional return path is suppressed by adding the balun device, the measurement results of different measurement methods are consistent and close to the realistic measurement results measured using a small device (maximum difference of 2.5 dB). This study addresses the accuracy of measurement results during MR-HBC channel gain measurements.