Synthesis of Flat-top Radiation Beam in a Cellular Network using FIR Filter Windowing Approach

In sub-6GHz cellular communication an agile beam synthesis is required specially when line of sight communication is not possible. Base station antennas of cellular communication serving a sector area must provide sufficient power and should minimize leakage of signal to adjacent sectors for faithful communication. The flat-top beam (FTB) pattern is used in sectored cellular networks, in multiple-input multiple-output (MIMO) systems and ensures a nearly constant gain in the desired cellular sector. In order to achieve flat-top beam, a combined beam synthesis technique, is suggested in this paper. The Fourier series (FS) method is used to obtain the flat-top beam in the desired sector for a planar dipole array and the Kaiser window filter (FSKW) is used to reduce the side lobe level (SLL). Using this method, a reduction of SLL of more than 30 dB is achieved compared to the traditional FS method for a flat-top beam of a planar dipole array, in addition to achieving almost no ripple on the top of the flat-top beam.