A cluster of many small holes with negative imaginary surface impedances may generate a negative refraction indexAlsaedi, Ahmed; Ahmad, Bashir; Challa, Durga Prasad; Kirane, Mokhtar; Sini, MouradMathematical methods in the applied sciences2016 / p. 3607-3622 : ill http://dx.doi.org/10.1002/mma.3805

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