A dual turn electrically coupled loop antenna is proposed to operate inside gastrointestinal capsules. The proposed structure is simple with a degree of freedom in design and compact size. In addition, it has low specific absorption rate (SAR) levels. Four different models have been designed to operate at industrial, scientific, medical (ISM) bands (433 MHz and 915 MHz). The first three antenna models with different sizes operate at the 433 MHz ISM band while the fourth antenna model operates at the 915 MHz ISM band. The primitive designs are performed by immersing the biocompatible-encapsulated prototypes inside the center of a cubic box of muscle phantom with an edge length of 100 mm. To mimic the realistic situation, the final designs were simulated inside a human torso model. As an experimental verification, a prototype has been fabricated and tested inside minced beef. The footprint size excluding the space in the core is 200 mm³. The peak SAR levels, averaged on 1 g, are 78.4, 51.8 and 81.67 W/kg for the three proposed antennas, respectively. The low SAR levels permit increasing the fed power to compensate medium losses in addition to obtain better imaging. The peak realized gains in muscle lie in the range of the other counterparts (− 19 dBi).

提出了一种双匝电耦合环形天线以在胃肠胶囊内部工作。所提出的结构简单，具有设计上的自由度和紧凑的尺寸。此外，它具有较低的比吸收率（SAR）水平。设计了四种不同的模型以在工业，科学，医学（ISM）频带（433 MHz和915 MHz）下运行。前三种尺寸不同的天线型号在433 MHz ISM频段上运行，而第四种天线型号在915 MHz ISM频段上运行。通过将生物相容性封装的原型浸入边缘长度为100 mm的立方体模型的体模中心内，可以执行原始设计。为了模拟现实情况，最终设计在人体躯干模型中进行了模拟。作为实验验证，原型已在牛肉碎中制造和测试。不含磁芯空间的占位面积为200毫米³。对于三种建议的天线，平均SAR峰值峰值平均为1 g，分别为78.4、51.8和81.67 W / kg。低SAR电平可以提高馈电功率，以补偿介质损耗，从而获得更好的成像效果。在肌肉中实现的最大峰值处于其他对应范围内（− 19 dBi）。