In this paper we introduce the concept of a free-space dielectric permittivity characterization method. The technique is suited particularly for such cases where the dimensions of the test material is several times larger than the excitation wavelength. The proposed method estimates permittivity using a plane wave excitation and multiple receiver antennas. The received power of the antennas are combined in order to estimate the parameters effectively. The weight factors for the combination are determined using multiple-output multiple-regression. The input data of the regression model is calculated using numerical simulations for the different parameter combinations. Results show that the proposed method yields good results when the conductivity of the material is known in advance, and has a limited use when the complex permittivity has to be estimated.