On-body polarization-controlled active antenna to enhance signal power in human dynamic channels

This paper presents a polarization-controlled active antenna applied to BAN on-body communications. A primal objective is to achieve the enhancement of signal power, not only in downlink but also in uplink dynamic channels, between an access point mounted on the wrist and a sensor module attached to various locations on a human body. Firstly, a dynamic channel model to represent the geometrical relationship between two locations considering arm-swinging motion was proposed. Based on the model, a weight function was derived to control an orthogonal active antenna in an adaptive way for increasing the radiation pattern in desired directions. The analytical results show that a high level of the received signal power can be obtained regardless of the armswing angle and antenna placement, confirming the effectiveness of the proposed method for BAN on-body communications.