Antenna characterization using reverberation chamber is being widely used and therefore several measurement techniques have been proposed. In this paper, the characterization technique based on two antennas is used in order to determine the radiation efficiency of a patch antenna. This work is conducted in two different configurations of a reverberation chamber (classical configuration and chaotic configuration). We evaluate the stirring techniques used (mechanical and frequential) in both configurations by calculating the number of independent samples. Statistical behavior of both cavity configurations (field homogeneity and isotropy) are also evaluated through the calculation of the enhanced backscatter parameter and the standard deviation of the measured parameters. Different measurements and calculation results are compared.