| 摘要 |
PCT No. PCT/GB95/02735 Sec. 371 Date May 22, 1997 Sec. 102(e) Date May 22, 1997 PCT Filed Nov. 23, 1995 PCT Pub. No. WO96/17404 PCT Pub. Date Jun. 6, 1996In accordance with the present invention, there is provided a linear antenna array comprising a number of antenna elements and a feed network, wherein the feed network is operable to apply the cumulative effect of a progressive phase shift across the antenna elements of the array and a stepped complex operator shift to selected groups of antenna elements of the array, whereby a down tilted and null-free coverage by a resulting radiation pattern can thereby be provided. The complex operator can be phase, amplitude or a combination of both. The antenna array can be a layered antenna and the phase shifts in the feed network can be provided by differing length transmission paths, whilst any amplitude shift can be provided by unequal power dividers. In order to provide no down tilt and just null fill-in, then the progressive phase shift can be specified to be zero.
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