Broad-band embroidered spiral antenna for off-body communications

An embroidered wearable spiral antenna is presented in this study. The spiral antenna is compact and flexible, yet has broad-band performance. The novelty of this study includes considering the antenna–body interaction rather than just considering the antenna alone. The antenna has been simulated and measured on a specific anthropomorphic mannequin torso phantom and a real person. The far-field on-body performance of the embroidered antenna on the phantom has been measured using a novel cylindrical near-field to far-field transformation technique. This technique allows the fast extraction of the full spherical radiation pattern and the corresponding far-field antenna characteristics on the human body without the need of rotating the phantom with expensive positioning systems. The on-body antenna performance including realised gain, directivity, radiation efficiency, radiation pattern and axial ratio have been presented.