A Compact Button Antenna with Dual-Band and Dual-Polarization for Wearable Body Area Networks

TL;DR

A new button antenna is designed for wearable devices, operating efficiently at two frequencies with different polarization types for body-area communications.

Contribution

The paper introduces a compact button antenna with dual-band and dual-polarization capabilities for wearable body area networks.

Findings

The antenna operates in the 2.45 GHz and 5.8 GHz ISM bands with linear and circular polarization.

Prototype measurements confirm robust performance in free-space and on-body settings.

SAR simulations show the antenna meets safety limits for wearable use.

Abstract

This paper presents a compact, dual-band, dual-polarization button antenna for Wireless Body Area Networks (WBANs) that operates in the 2.45 GHz and 5.8 GHz Industrial, Scientific, and Medical (ISM) bands. The antenna is engineered in the lower band from 2.33 to 2.8 GHz (18.3% fractional bandwidth) as a linearly polarized, top-loaded monopole, which provides an omnidirectional radiation pattern for on-body communication. In contrast, it functions as a cross-dipole in the higher band, achieving a fractional bandwidth of 66.4% (4.8–9.57 GHz) and a 3 dB axial ratio (AR) bandwidth of 57.4%, producing a broadside radiation with circular polarization for off-body communications. Prototype measurements in both free-space and on-body settings confirm the antenna’s robust performance, successfully validating its dual-band operation, dual-polarization characteristics. Furthermore, Specific Absorption Rate (SAR) simulations conducted on a human model demonstrate that the values are significantly below the established safety limits, confirming the antenna’s suitability for practical wearable applications.

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