In this article, a miniaturized dual-resonant antenna system at MHz-band operating at around 20 and 50 MHz is proposed for frequency-shift keying impulse radio (FSK-IR) intrabody communications. This antenna system comprises a swallowable helix-coil in-body antenna with a hollow cylindrical shape of 10 mm diameter and 30 mm length, and two single band on-body matched planar spiral-coil antennas with a compact size of 79 mm $\times\,\,72$ mm $\times\,\,2.8$ mm. For in-body antenna design, a nonuniform helical pitch structure is utilized to produce dual-resonant frequencies. The soft ferrite magnetic sheet with high relative permeability and low dissipation factor is used as a flexible conformal substrate to realize antenna miniaturization without lumped element loading. Simulation results for antenna performance, electromagnetic field distribution, and specific absorption rate are presented with different tissue-type phantoms, as well as an anatomical numerical human model. In addition, experimental verification of antenna performance and implant transmission characteristics is also conducted in a liquid phantom. At an implant depth of 50 mm, the measured maximum transmission coefficients are −33 and −45 dB at the dual-resonant frequency bands, respectively. Simulation and measurement results demonstrate that the proposed dual-resonant antenna is suitable for the FSK-IR system and can be expected to realize a data rate as high as 10 Mb/s for biomedical implant applications at MHz-band.

中文翻译：

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用于 FSK 脉冲无线电体内通信的 MHz 频段小型化双谐振螺旋/螺旋天线系统

在本文中，提出了一种工作在 20 和 50 MHz 左右的 MHz 频段的小型化双谐振天线系统，用于频移键控脉冲无线电 (FSK-IR) 体内通信。该天线系统包括一个直径为 10 毫米、长度为 30 毫米的空心圆柱形可吞咽螺旋线圈体内天线，以及两个尺寸为 79 毫米的单频段体上匹配平面螺旋线圈天线 $\times \,\,72$ 毫米 $\times\,\,2.8$ 毫米。对于体内天线设计，利用非均匀螺距结构来产生双谐振频率。采用具有高相对导磁率和低损耗因数的软铁氧体磁片作为柔性共形基板，实现天线小型化，无需集总元件负载。天线性能、电磁场分布、和特定的吸收率以不同的组织类型的体模以及解剖数字人体模型呈现。此外，天线性能和植入传输特性的实验验证也在液体模型中进行。在 50 mm 的植入深度处，测得的最大传输系数在双谐振频段分别为 -33 和 -45 dB。仿真和测量结果表明，所提出的双谐振天线适用于 FSK-IR 系统，并且有望在 MHz 波段为生物医学植入应用实现高达 10 Mb/s 的数据速率。天线性能和植入物传输特性的实验验证也在液体模型中进行。在 50 mm 的植入深度处，测得的最大传输系数在双谐振频段分别为 -33 和 -45 dB。仿真和测量结果表明，所提出的双谐振天线适用于 FSK-IR 系统，并且有望在 MHz 波段为生物医学植入应用实现高达 10 Mb/s 的数据速率。天线性能和植入物传输特性的实验验证也在液体模型中进行。在 50 mm 的植入深度处，测得的最大传输系数在双谐振频段分别为 -33 和 -45 dB。仿真和测量结果表明，所提出的双谐振天线适用于 FSK-IR 系统，并且有望在 MHz 波段为生物医学植入应用实现高达 10 Mb/s 的数据速率。