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THIRD ANNUAL
ASAP '95 WORKSHOP

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Propagation Measurements
for 1.9 GHz Antenna Array Design

Catherine M. Keller
MIT Lincoln Laboratory
244 Wood Street
Lexington, MA 02173-9108
email: keller@ll.mit.edu

Abstract This presentation addresses the benefits achievable with advanced base station antennas for 1.9 GHz Personal Communications Services (PCS). High-gain antennas, multiple subaperture diversity combining, and adaptive array processing (AAP) are all parts of the advanced antenna concept.

A measurement program was carried out in urban and suburban environments in order to specify PCS antenna array parameters. The objective of the measurement program is to determine the effects of antenna size on achievable gain, and therefore, on the size of the PCS cell. Antenna size is limited by the wavefront correlation distance. If an antenna dimension is large with respect to the correlation distance, then the full expected gain is not realized unless adaptive beamforming of subapertures is used. The results presented in this talk allow the size of the antenna elevation aperture to be determined so that fixed beamforming is sufficient to achieve high antenna gain. The results also provide a basis for estimating the effects of azimuth subarray separation on AAP performance.

The highlights of the study are: 1) large elevation apertures can effectively increase antenna gain, and it is reasonable to consider antennas that are up to eight meters tall; and 2) azimuth apertures should also be large for the purpose of achieving spatial diversity, but adaptive beamforming is needed to regain losses due to signal decorrelation.

This work was prepared under the Cooperative Research and Development Agreement (CRDA) collaboration between MIT Lincoln Laboratory and MCI. The measurements were made under an experimental license held by MCI. Special thanks go to R. Ferguson, D. Ridings, and J. Lee from MCI.

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