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Diversity Antennas for Base and Mobile Stations in Land Mobile Communication Systems
Yoshihide YAMADA Kenichi KAGOSHIMA Kouichi TSUNEKAWA
IEICE TRANSACTIONS on Communications
Publication Date: 1991/10/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section INVITED PAPER (Special Issue on Mobile Communication Antennas)
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Among many diversity schemes, space and radiation pattern diversity techniques are commonly used in mobile communication systems to overcome deep fading. A novel diagram is presented that clarifies the simultaneous effect of antenna spacing and radiation pattern on the correlation coefficient (ρe). It is shown that space diversity is more effective than radiation pattern diversity. Next, typical examples of practical diversity antenna configurations are shown. A novel configuration for an omnidirectional base station antenna for radiation pattern diversity is explained. Some configurations of space and radiation pattern diversity schemes are shown for mobile stations. A very compact diversity antenna configuration for portable phones is also shown. Finally, for the ease of designing diversity antenna, simple formulas for determining antenna spacing are developed. In the case of base station antennas, the ρe value is expressed by a simple SINC function with variables of spacing and the spread angle of multipath waves. Moreover, typical spread angles are clarified experimentally for Japanese urban areas. The appropriate antenna spacing for small ρe values is obtained. In the case of mobile station antennas, another simple formula is derived by taking into account the mutual coupling between diversity antennas.