Miniaturized on-body antenna for small and wearable brain microwave imaging systems

A miniaturized inset-fed on-body meandered bowtie antenna designed for brain microwave imaging systems is presented in this article. The proposed on-body antenna can contribute to the realization of a wearable and portable brain microwave imaging system. The size of 18 x 18 mm(2) is achieved at a frequency range of 0.75 to 4 GHz by the simultaneous use of self-complementary structures and meandered lines. The frequency band is a trade-off between penetration depth and spatial resolution. The proposed antenna performance was studied at different positions on the human head voxel model in terms of several parameters such as reflection coefficient, near-field directivity, and fidelity factor. In addition, the antenna bandwidth was surveyed on several volunteers using a wearable measurement setup. It has been found that the averages of measured reflection coefficients in different scenarios are in good agreement with the corresponding simulation results, and the antenna shows stable performance under different practical situations. The proposed antenna takes advantage of a small footprint and body matching, which make it an eligible choice for compact, portable, and wearable head microwave imaging systems.