A simple method to achieve multi-focus and pattern manipulation in antenna near field (NF) is proposed in this study, whose effectiveness is then validated by measurements based on different transmit-array antennas. The radiating aperture is divided into several regions and each region corresponds to one assigned focal point, thus achieving multi-focusing performance. Then, the superposition principle is employed and constrains the multiple foci into a certain area to get a contoured pattern. Three examples are investigated. Ant-A presents four balanced focal spots simultaneously, while Ant-B presents two unbalanced foci. A square flat-top field pattern is obtained for Ant-C. Three-dimensional printing technology is employed to fabricate these lenses, resulting in a low cost and light weight. Measured results coincide well with the numerical design and simulation. The proposed method provides a simple and effective alternative for NF power redistribution and owns great value in such applications as radio-frequency identification, wireless power transmission, millimetre-wave imaging etc.

中文翻译：

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基于三维打印发射阵列天线的近距离Ka波段多焦点和模式控制

本研究提出了一种在天线近场（NF）中实现多焦点和方向图操纵的简单方法，然后通过基于不同发射阵列天线的测量来验证其有效性。辐射孔被分成几个区域，每个区域对应一个分配的焦点，从而实现多聚焦性能。然后，采用叠加原理，将多个焦点限制在一定区域内，以得到轮廓图案。研究了三个例子。蚂蚁-A同时呈现四个平衡焦点，而蚂蚁-B呈现两个不平衡焦点。对于Ant-C，获得了正方形的平顶场图案。采用三维印刷技术来制造这些镜片，从而导致了低成本和轻量化。测量结果与数值设计和仿真吻合得很好。该方法为NF功率的重新分配提供了一种简单有效的替代方法，在射频识别，无线电力传输，毫米波成像等应用中具有重要的应用价值。