Effect of the leakage between elements on the measured capacity of indoor multiple-input multiple-output channels

RF switches are often used to measure individual path profiles in a multiple-antenna system. Leakage and other coupling between the antenna elements will deteriorate the channel capacity estimation accuracy. The analysis is performed to give a measure of the maximum tolerance for the leakage level of RF channel measurement systems. Leakage causes an underestimate of channel capacity that increases with the number of elements. The underestimate is negligible if leakage is less than –15 dB in a 4 by 4 antenna system. The more correlated the channels are, the less the effect of leakage. The result can also be used to indicate the design isolation requirements between receivers of a real system.