A low-profile compact dual-band L-shape monopole antenna is designed for microwave thorax imaging. The antenna operates at 433 and 915 MHz in Industrial, Scientific, and Medical band with a compact size of 30 mm × 20 mm × 1.5 mm, which is suitable for wearable devices. It radiates toward in-body direction. The monopole is bent to L-shape for miniaturization. A meandering shorted branch and an open branch are adopted to tune suitable resonance frequencies. The antenna is fabricated. Experiments are conducted with a phantom mimicking human model to verify the design. It is also tested with a human subject. With one antenna as transmitter and the other as receiver, the changes of S21 signals during respiration process verify the feasibility of respiration monitoring with this antenna. The antenna may be used in a microwave thorax imaging system in future research.

中文翻译：

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一种用于微波胸部监测的薄型紧凑型双频带 L 形单极天线

低剖面紧凑型双波段 L 形单极天线专为微波胸部成像而设计。该天线在工业、科学和医疗频段以 433 和 915 MHz 运行，尺寸紧凑，为 30 mm × 20 mm × 1.5 mm，适用于可穿戴设备。它向体内方向辐射。为了小型化，单极子弯曲成L形。采用曲折的短路支路和开路支路来调谐合适的谐振频率。天线制作完成。使用模拟人体模型的幻影进行实验以验证设计。它还用人类受试者进行了测试。一根天线作为发射器，另一根天线作为接收器，呼吸过程中S21信号的变化验证了用该天线监测呼吸的可行性。