It has been shown that diversity gains and MIMO capacity of multi-port antennas can be conveniently determined from reverberation chamber measurements. In this paper, we first present the covariance eigenvalue approach and the embedded far field function method to determine diversity gain and MIMO capacity, respectively, for arbitrary multi-port antennas. Then, we discuss the convergence of the covariance eigenvalue approach. In the end, we apply both methods to compare MRC diversity gains and MIMO capacity measured in a reverberation chamber (based on direct channel measurements) and an anechoic chamber (based on measurements of the embedded far field functions and efficiencies at all antenna ports). The comparison is performed over 2-8 GHz using a wideband multi-port antenna in two configurations. There are in general good agreements between the reverberation and anechoic chamber measurement results.