Closely spaced monopoles for mobile communications

The spatial cross-correlation function for antenna signals in multipath environments depends on the mutual coupling between the antennas. In general, this function is different from the spatial autocorrelation coefficient function of the multipath, fading field. This difference influences the design criteria for the element spacing of compact (that is, closely spaced elements) antennas. The relationship between the spatial autocorrelation function and the cross-correlation function is presented and used for practical, compact diversity antenna design