Wearable Dual-Band and Dual-Polarized Textile Antenna for On- and Off-Body Communications

A wearable all-textile microstrip patch antenna (MPA) operating in the dual bands of medical body area network (2.36-2.40 GHz) and WiMAX (3.4-3.6 GHz), is proposed for body-centric communications. The omnidirectional radiation pattern with linear polarization for on-body link and unidirectional radiation pattern with circular polarization for off-body link are achieved by introducing reactance loading into MPA. Notably, two pairs of shorting pins are employed to tune the TM
₁₀
mode of MPA and generate a new mode of TM
₀₀
, and by adjusting the spacing and radii of shorting pins, the required dual-band and dual-mode operation is achieved. Moreover, due to the adoption of textile (i.e., wool felt) as substrate and nylon conductive fabric as conductor, the antenna is flexible, totally conforming to the human body. The proposed MPA, with the dimensions of 70 mm × 70 mm × 2 mm (0.56λ
₀
× 0.56λ
₀
× 0.016λ
₀
at 2.38 GHz), was fabricated and characterized. The measured results show that the reflection coefficient, radiation pattern, and gain of the antenna are slightly affected by structural deformation and human body loading. With merit characteristics, the proposed design can be well applied to wearable medical applications.