为了提高双焦点透镜的扫描性能,提出了一种分层双焦点透镜设计,将双焦点透镜由单一介质改进为两种介质,增加了设计自由度,在相位控制的基础上调控口面场幅度分布,提高口面效率,增强扫描性能。利用粒子群优化算法,对形成该双焦点透镜两种介质分界面的透镜中间曲线参数进行优化,使口面场幅度分布更加均匀。优化设计的分层双焦点透镜在扫描±25°(8. 3 个波束宽度)时,可以实现边缘电平-7. 88 dB,增益损失为0. 43 dB,口面效率达到55. 8??。在同样扫描角度下,分层双焦点透镜相比平凸透镜增益损失减小1. 49 dB,相比单层双焦点增益损失减小0. 51 dB。当扫描角度进一步增大后,分层双焦点透镜相比单层双焦点透镜的优势更加明显,在扫描±35°(11. 3 个波束宽度)时相比单层双焦点透镜增益损失减小1. 35 dB,验证了分层双焦点透镜在扫描性能上的优势。

In order to improve the scanning performance of bifocal lens, a design of layered bifocal lens is proposed in this paper, which changed the bifocal lens from a single medium to two media. In this way, a design freedom is obtained and then used to control the amplitude distribution on the basis of phase control of the aperture field, finally the aperture efficiency is improved and the scanning performance is enhanced. Particle swarm optimization (PSO) algorithm is used to optimize the parameters of the interface between the two media of the bifocal lens, so as to make the amplitude distribution of the aperture field more uniform. At scanning angle of ±25°(8. 3 beamwidths), the edge level of -7. 88 dB, the gain loss of 0. 43 dB and the aperture efficiency up to 55. 8% can be achieved by the optimized layered bifocal lens. At the same scanning angle, the gain loss of the layered bifocal lens is 1. 49 dB lower than that of plano-convex lens, and 0. 51 dB lower than that of single-layer bifocal lens. When the scanning angle is further increased, the advantage of layered bifocal lens is more obvious than that of single-layer bifocal lens. The gain loss is reduced by 1. 35 dB at ±35°(11. 3 beamwidths) scanning, compared with that of single-layer bifocal lens, the advantages of layered bifocal lens in scanning performance are verified.

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