Contents I. Introduction
Biological media and tissues are highly dispersive at the microwave frequency range, and their complex permittivity is generally modeled by the Cole–Cole dispersion relation [1], [2]. With knowledge of tissue complex permittivity, the absorption of energy or the field distribution in tissue can be obtained from the solution of the Maxwell's equations using numerical techniques. In many applications, the solution in a narrow frequency band is desired, and the complex permittivity dispersion may not be considered. Examples are the prediction of the specific absorption rate (SAR) inside the head for its exposure to mobile phones radiation [3] and the analysis of biomedical antennas utilized in implanted devices [4]. On the other hand, broadband applications also exist, for which the dispersive nature of the tissues complex permittivity may need to be considered. As some examples, one can mention microwave radiometry [5]–[7] used in applications such as temperature monitoring during hyperthermia treatment of cancer, or the investigation of the interaction of ultra-wideband (UWB) pulses with biological matter [8], [9].
