Synthesized-Beam planar Antenna array for Earth Remote Sensing using SAR Systems

A planar array of 20 × 10 printed U-slot microstrip patch antennas is designed for the applications of high-resolution land-imaging using side-looking SAR systems operating in the C-band of the frequency. The planar array is designed to produce a three-dimensional beam of cosecant-squared shape in the ground-range direction and flat-topped shape in the azimuth direction. The mutual coupling between the adjacent patches is studied for investigating the controllability of the proposed array to achieve the required beam shapes. The desired radiation patterns are achieved by properly setting the complex excitation voltages of the array elements. A computationally-efficient Particle Swarm Optimization (PSO) algorithm is developed for this purpose. Instead of applying the PSO directly to obtain the excitation voltages of the entire planar array, which is computationally-expensive, it is applied to a 20-element and 10-element linear arrays to synthesize a cosecant-squared and flat-topped beams, respectively. Finally, the excitation voltages obtained from the optimization of the two linear arrays are simply used to determine voltage excitation of the entire planar array. The numerical solutions involved with the performance evaluation of the U-slot antenna, the mutual coupling between the elements of the array and the synthesized beam produced by the planar array for land imaging SAR applications are presented and discussed.