Compact bio‐inspired dual‐band uniplanar electromagnetic bandgap‐backed antenna for wearable applications

Abstract

A compact bio-inspired electromagnetic bandgap integrated wearable antenna (Bio-EBG-iwA) is proposed in this work. The Bio-EBG-iwA is based on the hybridization of semi-Vitis vinifera leaf-shaped patch, asymmetric feedline, reflected G-shaped slot, partial ground, and a stub on the ground plane. The antenna is built on the locally made textile material called Aso-oke (Alari) with permittivity and a loss tangent of 1.43 and 0.019, respectively. The dimension of the proposed antenna is 0.2 λ g × 0.1 λ g × 0.0089 λ g (22 mm × 12 mm × 0.7 mm) at 2.45 GHz. Despite its compactness, the gain of −0.48 and 2.5 dBi are achieved at 2.45 and 5.7 GHz respectively without electromagnetic bandgap (EBG). A dual-band textile-based uniplanar compact electromagnetic bandgap (UC-EBG) is introduced to create isolation between the human tissue and the antenna. The dual-band UC-EBG is realized through the use of a modified slitted-square ring (MSSR) and the 90° rotated H-shaped patch on Aso-oke (Alari) with a thickness of 2.1 mm. The periodicity of the proposed UC-EBG is 34.5 mm. The antenna is placed on a 2 × 2 array of the proposed UC-EBG separated by a 3 mm foam thickness. The radiation efficiency of 88.97% and 79.85% are achieved at 2.45 and 5.7 GHz respectively. The gain of the proposed UC-EBG integrated antenna increased from −0.48 and 2.5 dBi to 5.9 and 10.7 dBi at 2.45 and 5.7 GHz, respectively. The front-to-back ratio (FBR) of 26.3 dB is achieved with the use of UC-EBG. The use of UC-EBG results in a 98.31% and 99.4% reduction in average SAR at 2.45 and 5.7 GHz, respectively. The off-body and on-body performance analysis of the proposed UC-EBG integrated antenna show that the proposed EBG integrated antenna (Bio-EBG-iwA) is a suitable candidate for wearable application. To the best of our knowledge, this is the most compact wearable antenna with suitable gain, radiation efficiency, and high FBR. In addition, our proposed UC-EBG shows that slitting is an effective way of miniaturizing the EBG structure.