Reducing Waves on the Body Surface in Near-Field Medical Diagnostics by a Dielectric Rod Antenna

Artikel i vetenskaplig tidskrift, 2023

The multipath interference caused by the waves traveling on the body surface is a factor that limits the detection accuracy of microwave-based biomedical diagnostic systems. The waves traveling along these paths do not carry information of the area of interest, which is inside the body and are more sensitive to the changes in the space close to the antennas. In this paper for the first time, by placing a dielectric rod between the radiating element of the antenna and the body, the waves on the body surface are largely reduced while the antenna remains matched to the body. We design a Dielectric Rod Antenna (DRA) by deriving a 2-dimensional analytical solution of the wave propagation in a 2-layers cylindrical structure. The design is extended to 3D and further optimized using numerical simulations. It was shown that the addition of the dielectric rod enhances the field confinement by a factor of 2. The performance of the antenna, as verified by phantom measurements, shows that using the DRA increases the ratio of the transmission coefficient to power on the body surface to up to 24 dB and the antenna bandwidth is increased by 71% compared with the antenna without the dielectric rod.