Comparision of Polarization and Space Diversity in Operational Cellular and PCS Systems

Abstract

Antenna systems based on polarization diversity can be significantly smaller and easier to deploy than conventional vertically polarized horizontal space diversity systems. As such there is great interest in the substitution of polarization diversity for space diversity. This chapter compares and evaluates the efficacy of polarization diversity relative to the classic vertically polarized 20-wavelength, two-antenna space diversity configuration. It was observed that bottom line performance with a randomly oriented handheld unit was almost identical for polarization and space diversity systems. For a vertical mobile antenna the bottom line performance was approximately 3 dB worse for the polarization diversity system relative to the horizontal space diversity system with vertical polarization. Significant polarization discrimination, which is one slant favored over the other, was observed at close ranges (less than 1 km) when there is a nearly clear line of sight between mobile and base. Significant depolarization was observed at longer ranges and when the mobile is in the clutter.

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