Novel Multiband Antenna Design and Performance Evaluation for Wireless Electronic Capsule Systems

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 <tex-math notation="LaTeX">π × 8² ×</tex-math> 26 mm <tex-math notation="LaTeX">³</tex-math> , 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 <tex-math notation="LaTeX">$-$</tex-math> 405 MHz), Wireless Medical Telemetry Service (WMTS) band (1427 <tex-math notation="LaTeX">$-$</tex-math> 1432 MHz), and the Industrial, Scientific, and Medical (ISM) band (2.4 <tex-math notation="LaTeX">$-$</tex-math> 2.4835 GHz). The on-body receiving antennas have a planar spiral structure with a size of 20 × 6.8 × 27 mm <tex-math notation="LaTeX">³</tex-math> and a planar meandered structure with a size of 42 × 10 × 1.6 mm <tex-math notation="LaTeX">³</tex-math> , 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.