The first feature triggers many unusual phenomena like negative refraction, the reversed Doppler effect, and the reversed Cherenkov radiation, etc. The metamaterial has two main features: one being backward waves and another the amplification of evanescent waves. have demonstrated a growing evanescent wave in a dual-TL structure through simulation 12. The dual-Transmission-line(TL) structure is an analytical formulation that depicts the negative refraction of propagating waves and the growth of evanescent waves within a negative refractive index lens constructed with a periodical L, C loaded TL network 20. A medley of simulations of the full-wave and circuit demonstrating a grid of continual micro-strip transmission lines can forge evanescent waves in the lack of any lumped portions 19. In a slab with negative permittivity or negative permeability, it was shown that forward and backward evanescent surface waves occur 18. Pendry’s lens and related “growing exponential” and subwavelength imaging systems (see, e.g., 13, 14, 15, 16, 17). The study shows that the growing evanescent waves lead to the largest field amplitude at the second interface of the lens 12. It prevents them from increasing to unphysically enormous levels studied 11. In a realizable negative refractive index lens, the periodicity of the negative refractive index medium limits the amplitude of the rising evanescent waves. Pendry has shown how evanescent waves, which are effectively responsible for subwavelength resolution, may increase exponentially inside a well-built slab of double-negative (DNG) material, which is known as metamaterials, and how this effect can “compensate” for the fading exponential occurring outside the slab 10. In electromagnetic field theory, evanescent-wave coupling and the near field interaction are basically the same 1, 2, 3, 4, 5, 6, 7, 8, 9. In photonic and nanophotonic devices, evanescent wave coupling is frequently employed as waveguide sensors 1, 2, 3, 4, 5, 6, 7, 8, 9. If receiving waveguide supports modes of the proper frequency, the evanescent field generates propagating-wave modes, connecting (or coupling) the wave from one waveguide to the next 1, 2, 3, 4, 5, 6, 7, 8, 9. This coupling is often achieved by arranging two or more electromagnetic devices, such as optical waveguides, so close to each other that the evanescent field created by one element does not decay significantly before reaching the other. In optics, the transmitted field in total internal reflection is an evanescent wave 1, 2, 3, 4, 5, 6, 7, 8, 9, the evanescent-wave coupling is the technique of transmitting electromagnetic waves from one material to another 1, 2, 3, 4, 5, 6, 7, 8, 9. It can be represented mathematically by a wave vector with one or more of its components having an imaginary value. This is a near-field area phenomenon whose magnitude decays exponentially with increasing distance. An evanescent wave is an oscillating electric and/or magnetic field that does not travel as an electromagnetic wave instead, it is spatially concentrated around the source.
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