Polarization Properties of a Turnstile Antenna in the Vicinity of the Human Body

摘要

Polarization of a simple turnstile antenna situated close to the human body, for potential WBAN applications at 2.45 GHz band, is studied in detail by the use of electromagnetic simulator WIPL-D Pro. Circular polarization of the antenna (when isolated) is provided by adjusting the dipole impedances. Full-size, 3-dimensional simplified homogeneous model of a human body is applied. Polarization of both far and near field is studied, with various positions of the antenna and with/without metallic reflector. In the far field significant degradation of the circular polarization, due to the vicinity of the body, was observed. In the near field, at points close to the surface of the torso, polarization (of vector E) was found to significantly deviate from circular. Obtained results can be useful in designing on-body sensor networks in which circularly polarized antennas are applied, for both far field communication between sensor nodes and the gateway and near field communication between sensors.