An approach toward designing and building of a compact, low-profile, wideband, unidirectional, and conformal imaging antenna for electromagnetic (EM) head imaging systems is presented. The approach includes the realization of a custom-made flexible high-permittivity dielectric substrate to achieve a compact sensing antenna. The developed composite substrate is built using silicon-based poly-di-methyl-siloxane (PDMS) matrix and microscale of aluminium oxide (Al2O3) and graphite (G) powders. Al2O3 and G powders are used as fillers with different weight-ratio to manipulate and control the dielectric properties of the substrate for attaining better matched with the human head and reducing antenna’s physical size while keeping the PDMS flexibility feature. Using the custom-made substrate, a compact, wideband, and unidirectional on-body matched antenna for wearable EM head imaging system is realized. The antenna is configured as a multi-slot planar structure with four shorting pins, working as electric and magnetic dipoles at different frequency bands. The measured reflection coefficient (S11) shows an operating frequency band of 1–4.3 GHz. The time-average power density and the amplitude of the received signal inside the MRI-based realistic head phantom demonstrate a unidirectional propagation and high-fidelity factor (FF) of more than 90%. An array of 13 antennas are fabricated and tested on a realistic 3-D head phantom to verify the imaging capability of the proposed antenna. The reconstructed images of different targets inside the head phantom demonstrate the possibility of utilizing the conformal antenna arrays to detect and locate abnormality inside the brain using multistatic delay-multiply-and-sum beamforming algorithm.

中文翻译：

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基于柔性高介电常数定制基板的紧凑型单向共形天线，用于可穿戴宽带电磁头部成像系统

介绍了一种设计和构建用于电磁 (EM) 头部成像系统的紧凑、低剖面、宽带、单向和共形成像天线的方法。该方法包括实现定制的柔性高介电常数介电基板，以实现紧凑的传感天线。开发的复合基板是使用硅基聚二甲基硅氧烷 (PDMS) 基质和微米级氧化铝 (Al2O3) 和石墨 (G) 粉末构建的。Al2O3 和 G 粉末用作不同重量比的填料，以操纵和控制基板的介电性能，以实现与人头的更好匹配并减小天线的物理尺寸，同时保持 PDMS 的柔韧性特性。使用定制基板，紧凑、宽带、并实现了用于可穿戴EM头部成像系统的单向体匹配天线。天线配置为多槽平面结构，具有四个短路引脚，在不同频段充当电偶极子和磁偶极子。测得的反射系数 (S11) 显示工作频段为 1–4.3 GHz。基于 MRI 的真实头部体模内接收信号的时间平均功率密度和幅度表明单向传播和高保真因子 (FF) 超过 90%。在真实的 3-D 头部模型上制造和测试了 13 个天线阵列，以验证所提议天线的成像能力。