4. Conclusion

The concepts of metamaterials and negative refraction in artificial periodic structures, even though many of them were studied decades ago, have opened up new avenues of research in electromagnetism, thanks to both advances in technology and the fertile imagination of many researchers. In addition to telecommunications, the metamaterials used for submillimeter imaging are used in "competitive" fields of application such as medicine (to help diagnose skin diseases), security (to detect chemical or biological threats) and aeronautics. Nevertheless, depending on the wavelengths targeted, numerous studies remain to be carried out, both from a conceptual point of view (choice of patterns and gratings, metals versus dielectrics, chiral approaches, etc.) and on the structuring technologies to be developed, making it difficult to make precise predictions as to their large-scale development....