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A Slotted Waveguide Sparse Array with Four-Corner-Feed for Near-Field Focusing

This paper presents a double-layer four-corner-fed slotted waveguide sparse array antenna designed for the applications of near-field focusing. At the design frequency of 10 GHz, we achieve a good focusing effect at the focal point of 45 mm. Generally, it is difficult to realize the ideal phase distribution in the array antenna especially for short focal distance. The four-corner-feed structure associated with an appropriate waveguide dimension is adopted to realize approximately ideal phase distribution for a focus at 45mm. The residue phase error leads to the distinct degradation in the sidelobe level of the focal plane. The particle swarm optimization algorithm is introduced to further optimize the sidelobes and the focal spot in the focal plane for ideal focusing effect.