Hybrid Simulation-Measurement Method for Broadband Dielectric Characterization of Synthetic Human Head Tissues

This work proposes a broadband hybrid dielectric characterization method of lossy solid highly variable materials such as those employed in manufacturing realistic head phantoms for microwave imaging systems pre-clinical testing. The technique then recovers the permittivity and conductivity in the range of microwaves, posing the characterization as multi-objective optimization that exploits numerical and measured data. It copes with the intrinsic limitations of traditional dielectric characterization approaches while compensating for measuring errors, combining coaxial probe and double-ridged waveguide scattering measurements in a single scheme. Finally, the characterization is experimentally tested with mimicked head tissues made of custom-made graphite powder and polyurethane mixtures, retrieving their complex permittivity in the band from 1−4 GHz.