Investigation of dual-band antenna with low-SAR characteristics for bidirectional brain-machine interface applications

In this paper, we propose an innovative dual-band printed monopole antenna (PMA) for bidirectional brain machine interface (Bi-BMI) application. The proposed antenna configuration contains of a square radiator with a pair of rectangular slots and an inverted U-shaped slot and a truncated ground plane with a pair of Lshaped slots, which provides two usable radiating bands for down-link data transferring around 2.3-2.5 GHz and for up-link data transferring 3.21-9.03 GHz. By inserting two rectangular slots surrounded by a modified inverted U-shaped slot with modified dimensions on the radiating square patch and also by cutting two L-shaped slots, new resonances are created and therefore much wider impedance bandwidth can be generated at both lower and higher bands. Despite recently reported antenna designs in the literature, the proposed antenna demonstrates wideband radiative characteristics even at higher frequencies, and also the specific absorption rate (SAR) level in 1 mW input power case is satisfactory less than 0.4 W/kg in the whole radiating band. The designed antenna has a compact configuration and small size. Simulated and measured S-parameter and radiation patterns results are demonstrated to confirm the utility of the designed antenna configuration for brain machine interface application.