Wang, Zhiyu; Luo, Yu; Jiang, Tao; Wang, Zheng; Huangfu, Jiangtao; Ran, Lixin
Physical review letters Volume: 106 Issue: 4 2011. The paper experimentally demonstrated a microwave far-field image reconstruction modality with the transverse resolution exceeding the diffraction limit by using a single layer of highly nonlinear metamaterial. The harmonic fields of the nonlinear metamaterial surface allow the far-field propagation of wavefronts with spatial frequencies several times higher than that of the fundamental field. Near-field images can thus be mathematically recovered from the far-field patterns of the harmonic fields. 
