Wideband beam and null steering using a rectangular array of planar monopoles

Wideband multibeam formation using fully spatial signal processing for indoor communications

“…5 as shown in Figure 1 is adopted in this article. A rectangular antenna array, in which the array elements are spaced by half wavelength of highest frequency, is utilized.…”

“…Note that further detail of beamforming algorithm can be pursued in Ref. 5. The obtained weighting coefficients of this beamformer are real values.…”

“…As presented in Ref. 5, the objective function is produced using Sinc function [6]. As a result, only one main beam is achieved and the sidelobe levels are relatively high.…”

“…The practical realization of this beamformer has been presented in Ref. 5. However, this may introduce an energy loss in unused areas when utilizing for indoor purposes as it provides one broad main beam.…”

“…The plots of objective function obtained from (2) are demonstrated in Figures 2 and 3 when two and three directions of main beam are required, respectively. Note that a number of main beam directions presented in those figures is double as the symmetry of the objective function on u 1 -u 2 plane [5]. The objective function presented in Figure 2 is produced when having two main beam directions directed to À50 and 65 off boresight direction and 4 Â 4 array of omnidirectional antennas is used.…”