Polarization Diversity Antennas

In this study we investigate how different types of base station antenna polarization configurations, horizontal/vertical and slanted ±45 degrees, affect the diversity performance in different environments at 1800 MHz. The performance is determined by measurements where envelope cross-correlation, mean signal levels and diversity gain are studied in urban and suburban small-cell environments. The results are compared with a two branch space diversity scheme, where the antennas are horizontally separated by 20l. The correlation values are in general low, less than 0.7 for more than 90% of the measurements. The horizontal/vertical system suffers though from differences in mean branch signal levels, compared to the ± 45° and space diversity system which always have comparable mean signal levels. The diversity gain of both dual polarized antenna systems are in general about 1dB less than the gain of spatial diversity. The ± 45° scheme performs also about 1dB better than the horizontal/vertical scheme in the urban area. The results indicates that the ± 45° dual polarized scheme can be attractive in situations where hand-held portables are dimensioning for the cell planning.QCR 20181204