Sparse Focused Array Antenna Based on Subarrays

A focused array antenna (FAA) can concentrate its radiation power in a small spot in its Fresnel zone. Typically an FAA is fed by a multilevel power divider, which leads to a large insertion loss, especially for a large-scale FAA. Moreover, mutual coupling between closely arranged array elements and feedlines complicates the FAA design. In this letter, FAAs fed on the subarray level are proposed to get over the aforementioned problems. A 2 x 8 FAA is explored at 10 GHz, and the measured results show good agreements with the simulated ones except a 0.2-GHz frequency shift.