Synthesizing Shaped Beams with Prescribed Footprint Illumination for Specific Coverage Applications

Abstract

In many wireless personal communication applications such as medical microwave imaging, geostationary satellite, radar, and unmanned aerial vehicle communications, the shape of the radiated beam by an antenna array must be precisely matched to the required coverage area on the intended object to achieve maximum performance. In this paper, an iterative fast Fourier transform (IFFT) method is adopted for producing arbitrary targeted footprint patterns. The IFFT method exploits Fourier transform relationships to iteratively transform between array excitation weights and far-field radiation patterns, enabling fast and effective synthesis of complex shaped-beam footprints compared to all other optimization algorithms. For medical microwave imaging applications three different targeted footprints of triangular, square, and circular shapes are considered as samples, while for geostationary satellite applications, a complex footprint of Iraq-Map outline is considered. Simulation results have proved the effectiveness of the proposed method for efficiently generating the required footprints without the need for heavy optimization solvers. Moreover, some complicated coverage shapes such as the geographical outline of Iraq, require more degrees of freedom in the antenna array design, which increases both the cost and the array complexity. To solve this problem, a thinning method was used to remove array elements that have only a small influence on the overall radiation pattern.