Cross-polarized around-tower cellular antenna systems
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United States of America Patent
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-
May 2, 2000
Grant Date -
N/A
app pub date -
Jun 19, 1998
filing date -
Jun 19, 1998
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Omnidirectional cellular coverage may be provided by installing four 90 degree antennas on the sides of a tower. However, in a prior system pattern uniformity will be destroyed by nulling effects if the tower width causes the lateral separation between adjacent antennas to be large. Nulling effects in areas of overlap between beams of adjacent antennas are avoided by providing an omnidirectional pattern characterized by signal polarization which changes with azimuth. Cross polarization of adjacent antennas is achieved by providing North and South antennas with +45 degrees linear polarization and East and West antennas with -45 degrees linear polarization (alternating antennas with right and left circular polarizations may also be used). Portable cellular receivers for use with the antenna system may typically utilize antennas with either vertical or horizontal linear polarization. Polarization mismatches between transmitting and receiving antennas are partially offset by scattering effects in the vicinity of the cellular receiver.
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Cited Art Landscape
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