Measurements of the RF Power Absorption in Spheroidal Human and Animal Phantoms Exposed to the Near Field of a Dipole Source

Experimental results for the average specific absorption rate (SAR) in scaled spheroidal phantoms of human and animal models exposed to near-field radiation are presented. Prolate spheroidal phantoms filled with saline solution simulating muscle tissue were used to measure average SAR values in different models. To control the exposure conditions, simple sources of known radiation characteristics, namely, short electric dipoles, were used. The accuracy of the experimental procedure was evaluated by making several average SAR measuremens at large distances (0.6 ?) from the dipole. The results obtained are found to be in good agreement with those available in the Radiofrequency Radiation Dosimetry Handbook [2]. Near-field SAR measurements for different models are presented as a function of the distance from the source. It is shown that even for the complex radiation fields in the near zone of the source, the average SAR below the resonance frequency can be explained in tenns of the magnitude and direction of the incident fields in the same way that the plane wave absorption characteristics are explained.