Graduate Profiles 2012 - National University of Science and ...
Graduate Profiles 2012 - National University of Science and ...
Graduate Profiles 2012 - National University of Science and ...
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DESIGN & OPTIMIZATION OF ANTENNA ARRAY FOR WIMAX BASE STATIONTo increase the capacity <strong>and</strong> coverage in broadb<strong>and</strong> data communication according tothe IEEE 802.16e WiMAX st<strong>and</strong>ard, an intelligent base station antenna with beam- <strong>and</strong>null steering over a full circle is developed <strong>and</strong> optimized.In this report a circular antenna array <strong>of</strong> 8 vertical dipoles with a feeding network isdescribed, which provides m beams simultaneously in m directions for m subscriberswith a full coverage <strong>of</strong> 360°around the base station. By means <strong>of</strong> optimizationtechniques it is either possible to provide a null without ambiguity in every direction, orto optimize the side lobe attenuation by calculating the amplitudes <strong>and</strong> phases <strong>of</strong> everyantenna <strong>of</strong> the array.With this, detection finding or location based services are also possible.Conventional base station antennas in existing operational systems are eitheromnidirectional or placed in sectors. The greater part <strong>of</strong> the transmitted signal power isradiated into directions other than toward the specific user. This causes interference,reduces efficiency <strong>and</strong> the range <strong>of</strong> coverage. Especially in new broadb<strong>and</strong> services asWiMAX, where the user front-end is very simple, it becomes necessary to provide everyuser with a specific beam <strong>of</strong>fering enough gain to increase the range. It is also importantto reduce interference by other users or services by means <strong>of</strong> beam forming in a way,that either the side lobe attenuation <strong>of</strong> the base station antenna array as a whole isoptimized or by null steering. In rural areas a whole 360° degrees coverage around thebase station is desired. This leads to the solution introduced here <strong>of</strong> circular antennaarrays, a setup which can also be used for direction finding. The antenna array consists<strong>of</strong> n vertical dipoles equally spaced on a ring with diameter d. This building block isvertically stacked many times to achieve enough gain in the horizontal plane.Syndicate Members: Kashif EhsanHafiz Rasheed AhmedIlyas KhanSupervisor:Lec. Zeeshan Zahid34
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