This work presents the experimental verification of the power transmission of a radiating field into the human head for Microwave Imaging (MWI) applications. We aim at finding the range of frequencies that optimize the power scattered by any anomalies from inside to outside of the brain when excited by an incoming radiating field and hence improve the quality of microwave imaging. For this purpose, a 3D printed head phantom composed of liquids emulating dispersive biological head tissues in the range of [0.5-4]GHz has been built. Measurement results show that the wave penetrates well up to 1.3GHz as there is a strong attenuation around 2GHz, and low levels of transmitted power above 3GHz.