A Miniaturized Wearable Annular Slot Antenna Based on Designer LSPs for Telemedicine Communication

A compact multiband wearable antenna based on designer localized surface plasmons (designer LSPs) is proposed for future wireless body sensor networks (WBSNs). By periodically loading rectangular-corrugated metal-insulator-metal (MIM) structures that can support LSPs modes around the circular slit of an annular slot antenna, the antenna effectively reduces its dimension and achieves multiband characteristics. Meanwhile, an open S-shaped corrugated MIM waveguide structure is proposed for validating that the LSPs modes are originating from the Fabry-Perot resonances. Furthermore, a circular metallic disk is introduced at the end of the microstrip feedline, which can enhance electromagnetic energy coupling and improve impedance matching and radiation efficiency. Simulated and measured results demonstrate that the proposed antenna produces five operating bands, including 1.60–1.64 GHz, 3.49–3.58 GHz, 4.78–5.01 GHz, 6.16–6.63 GHz, and 7.25–7.61 GHz, with a peak gain of 5.19 dBi. The antenna dimension is only
$45\times 40$
mm (about
$0.24~\lambda $
g
$\times 0.21~\lambda $
g). The maximum specific absorption rate (SAR) value of human tissue complies with IEEE guidelines for safety radiation standards. This work explores the far-field radiation characteristics of designer LSPs in wearable antennas, which can find many applications, including healthcare monitoring systems and telemedicine communication fields.