A Novel Active Anapole Independent of High Permittivity Material

In this paper, a novel active anapole independent of high permittivity material has been designed. It consists of a linear current source and eight loop current sources. By adjusting the magnitude and phase distribution of these two types of sources, the electric dipole moment and toroidal dipole moment are configured to meet the conditions for anapole, thus an anapole state with no far-field radiation is realized. In contrast to passive anapoles excited by incident plane waves, the proposed anapole is achieved by active feeding, allowing for more flexible control methods. Furthermore, there is no need of high permittivity materials in constructing the anapole, and thereby the robustness in diverse electromagnetic environments is improved. The simulation results indicate that the radiation gain of the proposed anapole is low to -28.5 dB and is significantly lower than those of the linear or loop current source fed individually, which demonstrate its anapole characteristics.