Slot Antenna in Cylindrical Coupling Brick for Microwave Brain Imaging

In this contribution, two antennas for microwave imaging are described and validated. The first solution is a slot antenna designed when it works a direct contact with human head. However, the air-gap issues and hair layer degrade the antenna performances. These limitations are overcome with the cylindrical brick antenna containing coupling liquid medium. Basically, this antenna consists of a ground plane hosting a wide slot and a microstrip feed line with a fork-like tuning stub inserted within the circular container. Numerical examples show that the proposed antenna exhibits S11below −10 dB over the selected frequency band from 1 to 2 GHz, in agreement with microwave brain imaging systems. Moreover, the antenna is assessed in terms of transmission coefficients and field penetration. In particular, it is shown that such a feature holds true when the antenna is placed in different positions over the head, when it is located on both the skin and hair. Experiments on a few real humans confirm the numerical results. The transmission coefficient, which is the only one used in imaging systems to streamline the hardware complexity, is of comparable level of other similar antennas already present in literature. However, the proposed antenna is lighter and smaller in size.