Novel Multiband Antenna Design and Performance Evaluation for Wireless Electronic Capsule Systems
Hailian Liu, Jingjing Shi, L. Song, Lijia Liu, Yukang Wang, Tonglei Cheng, Jianqing Wang
Abstract
In this work, a novel miniaturized multi-resonant conformal antenna system has been proposed for wireless electronic capsule applications. It consists of a swallowable in-body antenna and two kinds of spiral/meandering on-body antennas with a simple structure and a low profile. The in-body transmitting antenna has a hollow cylinder-like structure with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pi \times 8^{2} \times$</tex-math></inline-formula> 26 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> , which is a combination of a helical spiral conformed on a flexible substrate and a planar spiral on a high dielectric substrate, to generate multi-resonant frequencies. It operates in three bands, Medical Implanted Communication Service (MICS) band (402 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 405 MHz), Wireless Medical Telemetry Service (WMTS) band (1427 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 1432 MHz), and the Industrial, Scientific, and Medical (ISM) band (2.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 2.4835 GHz). The on-body receiving antennas have a planar spiral structure with a size of 20 × 6.8 × 27 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> and a planar meandered structure with a size of 42 × 10 × 1.6 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> , respectively, which are suitable for wearable terminals. The performance of the proposed antenna system is analyzed and validated using a muscle-equivalent model, a multi-layer tissue model, a numerical human model in simulations, and a liquid phantom in experiments. Simulation and experimental results show the good potential of the antenna system for intra-body communication scenarios such as wireless electronic capsules.