Fig. 2

(a)-(d) The proposed four kinds of meta-atoms. The parameters are optimized as: the periodical length of 6.0 mm, r₁ = 2.5 mm, r₂ = 2.0 mm, l = 1.4 mm, g = 1.2 mm, and d = 0.3 mm. (e)-(h) Amplitude responses of the four kinds of meta-atom. r_LL and r_RR represent the co-polarized amplitude under the incidence of left-handed and right-handed circularly polarized waves. (i)-(l) Phase responses of the four kinds of meta-atom when varistor diodes are operated at “On” states. The φ_LL and φ_RR represent the phase of output co-polarized component under the incidence of left-handed and right-handed circularly polarized waves