Signal Interference Analysis Model In Near-Field Coupling Communication

Near-field coupling communication (NFCC) is a technology that uses the surface of the human body as a transmission path. To suppress the radiation signal from the human body, NFCC devices use a carrier frequency of less than 10 MHz. Because the radiation signal has the potential to disturb the other NFCC links, the radiation signal from other devices needs to be suppressed to ensure stable NFCC links. This paper describes our investigation of the interfering mechanism in NFCC systems to put the systems into practical use, such as at a ticket gate in the train station. We measured interference signal losses depending on the distance between two phantoms, regarded as human bodies. Based on the experimental and simulated results, an equivalent circuit of the signal interference was proposed. From the interference analytical model, we identified the capacitance that caused the interference problem and found that weakening the effects of this capacitance was important to achieve a stable NFCC link.