An open-ended coaxial probe (OECP) model originally proposed by Raicu is evaluated analytically giving a new insight. The virtual transmission line model (VTLM) is extended taking into account three layers (liquid layer, tissue, deep tissue) or four layers (non-conducting foil, liquid layer, tissue, deep tissue) depending on an application to be evaluated practically be means of an impedance analyzer with a proper dielectric interface. The analytical evaluation permits to take into account the dielectric response phenomena occurring in each layer separately. Additionally, there is no need for the electrode polarization impedance effect reduction by means of the analytical technique proposed by Schwan due to the galvanic isolation of the tissue - probe tip interface by the non-conducting foil.