A study of the antenna array configuration of an M-branch diversity combining mobile radio receiver

The theoretical analysis in this paper is based on the assumption that the angles of signal arrival on the mobile receiver are uniformly distributed. From the analysis and experimental studies, we find that if the antenna spacing between two adjacent antennas in a space diversity array is greater than 0.5λ the array configuration does not affect the cumulative distribution curves nor the shapes of the level-crossing-rate (LCR) curves, and only slightly affects the signal level at which the maximum LCR occurs. Hence a three-element array with a triangular shape or a four-element array with a rectangular shape can be considered a good arrangement, provided each side (antenna spacing) is greater than 0.5λ. Two slightly better arrangements than those we just mentioned for improving the signal fading are also proposed for three-branch and four-branch diversity signals, respectively.