A Comprehensive Analysis of Low-Profile Dual Band Flexible Omnidirectional Wearable Antenna for WBAN Applications

Abstract

This manuscript demonstrates a comprehensive analysis of a low-profile dual-band flexible omnidirectional wearable antenna, designed for Wireless Body Area Network (WBAN) applications. The proposed antenna is designed and fabricated on a commercially available semiflexible RT/duroid 5870 substrate. The antenna prototype is composed of a circular radiating patch with a star-shaped slot at the center, providing dual-band operations that resonates at the 2.45 GHz ISM band and 5.2 GHz WLAN band. Meanwhile, two truncated arc-shaped slots at the top and bottom edges of the radiating patch and the partial ground were utilized to improve the reflection coefficients (S11) and impedance bandwidth of the antenna. The proposed antenna has a compact footprint of $47\times 30\times 0.787$ mm3 ( $0.38~\lambda \text{o} \times 0.25~\lambda \text{o} \times 0.006~\lambda \text{o}$ at 2.45 GHz), with measured impedance bandwidth of 48% and 38.5% at 2.45 GHz and 5.2 GHz respectively. Moreover, the designed antenna has an omnidirectional and bidirectional radiation feature with the estimated gain of 2.5 dBi, 4.63 dBi and numerical efficiencies of 98.5% and 95% at 2.45 GHz and 5.2 GHz respectively. Furthermore, a comprehensive investigation encompassing a specific absorption rate and an exploration of bending aspects validated the effectiveness of the suggested design in adhering the SAR threshold and its remarkable robustness, when confronted with the demands imposed by human body loading and structural deformations. Consequently, both the numerical and measured results strongly endorse the significance of the suggested design for lightweight, body-worn wearable devices within the Wireless Body Area Network applications.

Keywords

• Dual band
• microstrip patch antenna
• omnidirectional antenna
• SAR
• WBAN