Dual-Band Flexible MIMO Antenna with Self-Isolation Enhancement Structure for Wearable Applications

A two-element dual-band flexible multi-in multi-out antenna which can be used for wearable applications is proposed in this paper. The antenna consists of two radiating elements fed by coplanar waveguide, and a shielding layer, which are all made of flexible conductive cloth MKKTN260. Each radiating element is composed of two coupled split ring-shaped bending strips. The proposed antenna shows two measured impedance bandwidth (S₁₁<−10 dB) of 2.39–2.48 GHz and 5.72–5.88 GHz, so that it can be used for 2.4 GHz and 5.8 GHz ISM (industrial scientific medical) applications. The two coupled split rings form a self-isolation enhancement structure and can realize polarization diversity at 2.4 GHz band and radiation shielding at 5.8 GHz band, respectively. High isolation (>30 dB) has been achieved for both the bands. Other characteristics for wearable applications like gain, efficiency, specific absorption rate, and bending performances were also studied.