Using magnetically-coupled structures of subwavelength metallic helices, we demonstrate superdirective end-fire radiation in the low GHz frequency range. Numerical, experimental and analytical results are presented on superdirective dimers that are almost three times smaller compared to previously demonstrated dimers of split-ring-resonators (0.09 compared with 0.25) and provide close to theoretical maximum values of directivity without using complex feeding networks. Optimisation of such structures in terms of their size, directivity, efficiency and operational passband width is demonstrated.

中文翻译：

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螺旋元素二聚体的微波超指向性

使用亚波长金属螺旋的磁耦合结构，我们演示了低GHz频率范围内的超指向性端射辐射。超定向二聚体的数值，实验和分析结果均比以前证明的开环谐振器二聚体小三倍（0.09与0.25相比），并且在不使用复杂进料网络的情况下提供了接近理论上最大的方向性值。展示了这种结构在尺寸，方向性，效率和工作通带宽度方面的优化。