This article presents a novel pattern-reconfigurable antenna based on theory of characteristic mode for body area networks (BAN) communication. The radiation pattern of the antenna is able to switch between the omnidirectional pattern and broadside pattern, which can satisfy on-body and off-body communication links simultaneously. An array of 4 × 2 rectangular plates with the off-body communication mode at BAN frequency band is used as the main radiator, and four copper posts between the radiator and the ground are introduced to generate the on-body mode. A simple feeding network is designed to selectively excite the two modes. The footprint of the proposed antenna is 0.43 λ₀ × 0.43 λ₀ × 0.05 λ₀. For demonstration, the proposed antenna has been fabricated and measured both in the free space and on the phantom. The measured results agree well with the simulated ones. Furthermore, the issue of the specific absorption rate (SAR) is studied. The peak SAR values of the proposed antenna in two communication modes are far below the Federal Communication Commission standard. In addition, for practical application, the link budget of the on-body link is investigated. The stable impedance and radiation properties, the low SAR values and the reliable communication ability make the proposed antenna be a suitable candidate for BAN communications.

中文翻译：

---

一种用于体域网通信的模式可重构天线设计

本文提出了一种基于特征模式理论的新型模式可重构天线，用于体域网 (BAN) 通信。天线的辐射方向图能够在全向方向图和宽边方向图之间切换，可以同时满足在体和离体通信链路。采用BAN频段离体通信模式的4×2矩形板阵列作为主辐射体，在辐射体与地之间引入4根铜柱产生在体模式。设计了一个简单的馈电网络来选择性地激发这两种模式。建议天线的足迹为 0.43 λ ₀  × 0.43 λ ₀  × 0.05 λ ₀. 为了演示，建议的天线已经在自由空间和体模上制造和测量。实测结果与模拟结果吻合良好。此外，研究了比吸收率（SAR）的问题。两种通信模式下建议天线的峰值 SAR 值远低于联邦通信委员会标准。此外，针对实际应用，研究了在体链路的链路预算。稳定的阻抗和辐射特性、低 SAR 值和可靠的通信能力使所提出的天线成为 BAN 通信的合适候选者。