Field of the circular focused aperture radiating into the material medium

The problems go back to antennas designing for medical application (applicators) considerably differ from those that take place at the radiating in free space antennas designing. The main reason producing these differences lies in the fact that the biological medium contacting with antennas is absorbing and moreover have of great value of the dielectric permeability real part. In connection with the fast attenuation of the field, propagating in the medium depth, the near zone and Fresnel zone roles essentially increases. The field distribution character information in these zones is especially important in applicators designing intended for hyperthermia. In the paper results of the development of an applicator mathematical model as the circular aperture, which is in the contact with the material medium and research of the field distribution special features in Fresnel zone, in particular, of its availability and efficient focusing within the limits of the given zone are given.