Integrative implementation of scattering reduction and radiation enhancement for an electrically small antenna by subwavelength plasmas

The integrative design of scattering and radiation characteristics of antennas is of great practical significance for modern wireless communication. In this work, from the perspective of separate and cooperative modes, we comprehensively discussed the possibility of simultaneously and harmoniously implementing scattering suppression and radiation enhancement for an electrically small antenna by subwavelength plasmas. For the separate mode where the two functions are decoupled based on a two-layer structure, it is shown that an overdense-underdense core-shell density profile is preferred to achieve the optimal synergism between radiation enhancement and plasmonic-cloaking-induced invisibility, where the angular frequency of detecting waves (ω_d) is supposed to be lower than that of communication signals (ω_c). For the cooperative mode where the two functions are coupled within one plasma shell, the collaborative strategies between plasmonic-cloaking/Fano-resonance-induced invisibility and radiation enhancement are analyzed. The results show that the plasmonic-cloaking type requires ω_d > ω_c, while for the Fano-resonance type, ω_d is larger/less than ω_c when radiation enhancement is dominated by the symmetrically/asymmetrically coupled plasmon modes. Also, we provided clearer perspectives to distinguish the physical differences between plasmonic-cloaking and Fano-resonance-induced invisibility and between radiation enhancement underlying the two modes. Our results provide promising solutions for designing next-generation plasma-based tunable and intelligent stealth antennas.