Thin profile UWB antenna with improved bandwidth for wearable applications

Abstract This work investigates a compact tapered Coplanar Waveguide (CPW) fed wearable antenna. The wide band antenna incorporates a modified patch inspired by a flower shape and a semi-elliptical ground plane to realize a wide bandwidth. The flower-shaped geometry is implemented to increase the electrical perimeter of the radiating element to improve impedance bandwidth. The antenna design is also elaborated by mathematical and analytical modeling. The antenna prototype is printed on a thin FR-4 (0.0026 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> </mml:math> thick) substrate with an overall footprint of 0.21 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> </mml:math> × 0.28 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> </mml:math> (where <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>λ</mml:mi> </mml:math> is the lower operating wavelength of the proposed structure, i.e., f = 3.95 GHz). The measured results, like reflection coefficient, far-field plots, and gain, are compared with the simulated results. The measured bandwidth is 19.92 GHz with a gain of 3.9 dBi. An investigation is carried out underwater to analyze the performance of the antenna in wet conditions. Specific Absorption Rate (SAR) is calculated to ensure the safety of human tissue with antenna proximity. The maximum SAR observed is 0.844 W kg −1 , within the acceptable limit. Thus, the reported results validate the application of the proposed antenna for wearable devices and sensors.