Frequency Detuning and Performance Analysis in Circularly Polarized Dual-Band Wearable Antenna for Body Area Networks under Bending Conditions

A compact dual-band antenna designed and operates inside the ISM ranges at 2.4 GHz and 5.8 GHz for Body Area Network (BAN) applications. Built on a flexible fabric felt substrate(εr = 1.2, tanδ = 0.02), its modest size of 20 x 17 x 2 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> shows a circular form with triangular gaps for dual-band operation. With peak gains of 3.5 dBi and 3.8 dBi correspondingly and efficiencies of 80% and 83%, respectively, the antenna reaches bandwidths of 28% (2.2–3.1 GHz) and 18% (5.1–6 GHz). Its fit for wearable uses is improved by circular polarization and steady omnidirectional radiation patterns. Under several conditions, bending analysis and experimental validation demonstrate its consistent performance by evaluating important characteristics like gain, radiation patterns, return loss, and frequency detuning.