Maximizing Signal-to-Noise Ratio in the Presence of Coil Coupling

Crosstalk due to coupling produces noise correlation between receiver coils. It has been stated that this correlation reduces the signal-to-noise ratio obtainable from combining signals from the coils. In this paper, it is shown that the effects of crosstalk on the signal-to-noise ratio may in theory be eliminated by properly combining signals. Equations are derived which show how the signals from two coils should be combined in the presence of crosstalk in order to obtain the same signal-to-noise ratio as in an ideal case of no crosstalk. The deviation from optimum signal-to-noise ratio due to imperfect circuits and amplifiers is discussed. An experimental technique for achieving the proper combination of signals is presented.