Biblio

This manuscript prescribes the design of a four-port ultra-wideband (UWB) diversity antenna combined with 2.4 GHz ISM radio band. The denim-based wearable antenna is intended for use as a radio frequency identification (RFID) tag for tracking and security applications. The unit cells of the antenna are arranged orthogonally to each other to achieve isolation \$\textbackslashtextbackslashgt15\$ dB. The bending analysis of the proposed antenna is performed to ensure its stability. The dimensions of the unit cell and four-port MIMO antenna are \$30 \textbackslashtextbackslashtimes 17 \textbackslashtextbackslashtimes 1\$ cubic millimeter and \$55 \textbackslashtextbackslashtimes 53 \textbackslashtextbackslashtimes 1\$ cubic millimeter, respectively. The proposed antenna’s specific absorption rate (SAR) is researched in order to determine the safer SAR limit set by the Federal Communications Commission (FCC).

Numerous antenna design approaches for wearable applications have been investigated in the literature. As on-body wearable communications become more ingrained in our daily activities, the necessity to investigate the impacts of these networks burgeons as a major requirement. In this study, we investigate the human electromagnetic field (EMF) exposure effect from on-body wearable devices at 2.4 GHz and 60 GHz, and compare the results to illustrate how the technology evolution to higher frequencies from wearable communications can impact our health. Our results suggest the average specific absorption rate (SAR) at 60 GHz can exceed the regulatory guidelines within a certain separation distance between a wearable device and the human skin surface. To the best of authors' knowledge, this is the first work that explicitly compares the human EMF exposure at different operating frequencies for on-body wearable communications, which provides a direct roadmap in design of wearable devices to be deployed in the Internet of Battlefield Things (IoBT).