Wideband Wearable Antenna for Biomedical Telemetry Applications

This paper presents a wideband, low-profile and semi-flexible antenna for wearable biomedical telemetry applications. The antenna is designed on a semi-flexible material of RT/duroid 5880 (<inline-formula> <tex-math notation="LaTeX">$\epsilon _{r} = 2.2$ </tex-math></inline-formula>, tan<inline-formula> <tex-math notation="LaTeX">$\delta = 0.0004$ </tex-math></inline-formula>) with an overall dimensions of 17 mm <inline-formula> <tex-math notation="LaTeX">$\times25$ </tex-math></inline-formula> mm <inline-formula> <tex-math notation="LaTeX">$\times0.787$ </tex-math></inline-formula> mm (<inline-formula> <tex-math notation="LaTeX">$0.2\lambda _{\circ }\times 0.29\lambda _{\circ }\times 0.009\lambda _{\circ }$ </tex-math></inline-formula>). A conventional rectangular patch is modified by adding rectangular slots to lower the resonant frequency, and the partial ground plane is modified to enhance the operational bandwidth. The final antenna model operates at 2.4 GHz with a 10-dB bandwidth (fractional bandwidth) of 1380 MHz (59.7 % at the centre frequency of 2.4 GHz). The proposed antenna maintains high gain (2.50 dBi at 2.4 GHz) and efficiency (93 % at 2.4 GHz). It is proved from the simulations and experimental results that the antenna has negligible effects in terms of reflection coefficient, bandwidth, gain, and efficiency when it is bent. Moreover, the antenna is simulated and experimentally tested in proximity of the human body, which shows good performance. The proposed wideband antenna is a promising candidate for compact wearable biomedical devices.