Study On Near-Field Target Detection And Imaging By Using Flat Left Handed Metamaterial Lens

Recently, a novel artificial material named Left Handed Metamaterial (LHM) with unique properties of simultaneously negative permittivity and permeability has attracted great attention. Because of the characteristic of negative refraction, a flat LHM slab can act as a lens. It should be noted that the perfect lens enables one to obtain an ideal image of a point source and achieves a sub-wavelength resolution.In this dissertation, detailed analysis of focusing property by using LHM slab is conducted in light of the plane-wave expansion theory. We studied numerically, by means of FDTD method, the focusing resolution considering the impacts of different thickness, different loss and different refraction index mismatch. By recording the backscattered field intensity from a PEC cylinder in vacuum and in media, respectively, a significant enhancement is introduced.It is demonstrated that LHM slab can not only focus the electromagnetic wave emitted from the point source, but also refocus the backscattered wave from the target. In contrast to the conventional lens with curved surfaces, the focus point of flat LHM lens is not fixed. Thus, a scheme for target detection and imaging is proposed by scanning the focus. It has been found that the proposed scheme can be carried out without the time-consuming data processing. The sub-wavelength imaging resolution is obtained and the backscattered field from a small target is enhanced remarkably by LHM flat lens. Considering the rapid development in artificial LHM design, LHM lens can be applied to numerous situations of near-field target detection and imaging, such as the early breast tumor detection.