Vertically-and horizontally-polarized antennas were investigated for on-body to on-body (OB2OB), in-body to in-body (IB2IB), and on-body to in-body (OB2IB) wireless propagations at frequencies of 915 MHz and 2.45 GHz. Theoretical formulations, simulations, and measurements were employed to study the effect of source antenna orientation on the attenuation of the radio frequency (RF) wave as it propagates around, inside, and through the body near the torso region. The results show that the vertical polarization is preferred for OB2OB communication, and the horizontal polarization is better for IB2IB communication. Furthermore, the dominant propagation mechanism and optimum antenna excitation for OB2IB communication are identified to be distance-dependent. The horizontallypolarized dipole is preferred at a shorter distance while the vertically-polarized dipole is preferred at a larger distance away from the source. The observed results were explained using the estimated attenuation rates of the different propagation mechanisms.

E-textile antennas have the potential to be the premier on-body wearable sensor. Embroidery techniques, which can be applied to produce e-textile antennas, assist in large production volumes and fast production speeds. This paper focuses on the effects of three commonly used embroidery parameters, namely stitch type, conductive thread location, and stabilizer, on the performance of embroidered dipole antennas in order to determine the ideal embroidery combination for optimal antenna performance. Fifty-four dipole antenna samples were fabricated and measured at the industrial, scientific, and medical (ISM) frequency band of 2.45 GHz. The results of this study show that machine-embroidered antenna designs with satin stitches resonate at a lower frequency and exhibit a lower transmission gain compared with those made with contour stiches, and the conductive thread location in the bobbin location plus the use of a water-soluble stabilizer can help improve impedance matching.

The field of wireless body area networks (WBANs) has seen growing interest in recent years due to applications of wearable devices, such as in healthcare. Effective on-body antenna design is necessary to provide optimal performance in real-world scenarios. This study compares several wearable antenna types, which are monopole, patch, and e-textile antennas, to determine how human body motion affects antenna performance using a human body phantom model and human volunteers. Monopole antenna overall outperforms the patch antenna at 915 MHz and the e-textile antenna at 2.45 GHz, and a Weibull distribution can be used as a probability distribution for S 21 during an arm swing motion for all antenna types tested.

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