In scalar coherence theory,the van Cittert-Zernike theorem plays an importance role for studying the propagation processes of partially coherent fields.In the past few years,a lot of work has been done to describe an extension of the van Cittert-Zernike theorem in terms of the 2? matrix to examine coherence and polarization properties of the field generated by a partially polarized incoherent electromagnetic beam.In this paper,we would like to experimentally demonstrate the unified theory of coherence and polarization of random electromagnetic beams by a modified radial shearing interferometer,which may be regarded as a tensor version of van Cittert-Zernike theorem.The experimental results show that the mutual intensity matrix of the electromagnetic field produced by a polarized incoherent source increases on propagation whereas the degree of the polarization remains unchanged.