Microstrip array antenna for precise near-field focusing

An array of microstrip antennas is introduced to achieve precise near-field focusing. A precise focusing approach of synthesising weights for array excitations is employed in the proposed near-field-focused (NFF) array, consisting of 3 × 3 subarrays. The usage of this approach allows the beam angle of every subarray to point to the focal spot precisely at the working frequency of 10 GHz. By introducing this working mechanism, a good trade-off has been achieved in the performance. The design can form a small focal width, about 6.6 mm, with a small location error of the focal spot of 8%. Meanwhile, the sidelobe level and the aperture remain small. To establish the effectiveness of this approach, we have designed, simulated, and measured this work.