Direct Antenna Modulation (DAM) for Enhanced Capacity Performance of Near-Field Communication (NFC) Link

Shannon´s theorem suggests that the capacity of a wireless link is determined by both the power received and the bandwidth of the system. However, in a conventional setup of an inductively coupled near-field communication (NFC) link, there is a trade-off between the power coupled through and the bandwidth. Direct antenna modulation (DAM) is a feasible scheme to mitigate this dilemma. With DAM utilized in a NFC link, the power and bandwidth product limit in a high Q system can be circumvented because the non-linear/time-varying nature of the operation allows high speed modulations decoupled from the charging and discharging process of the high-Q resonator. In this paper, the theory of NFC link with DAM on the transmitter is presented and validated with an experimental setup. Improvement in reception of the high-speed modulation information is observed in the experiment, implying that a superior capacity performance of a NFC link is achieved through DAM versus the traditional scheme.