The Theory, The Design And The Systemic Application Of Metasurfaces

The metasurfaces can be considered as the two-dimension plane metamaterials. The metasurfaces are the period or the quasi-period surface structures which are composed of the sub-wavelength unit cells arranged under the special regularity. Compared to the bulk metamaterials, the metasurfaces have the advantages such as small volume, low-profile, low-loss, low-cost and easily conformal, so they have played a huge role in controlling the electromagnetic wave and can be the research hot spot and focus in relevant subjects of electromagnetic field in recent years. Some mainstream theoretical modeling methods of metasurfaces are introduced in detail. Based on the technology of metasurfaces, some new kinds of electromagnetic devices and new concept of designing the new electromagnetic systems are proposed. The main researches of this dissertation are following:1) Based on the isotropic unit cell, the method of designing the surface wave non-diffraction Bessel-lens verified in the experiment is presented. This method utilize the composite lens (the half Maxwell fisheye lens adding the plane lens) to generate the Bessel beam directly under the excitation of point source.2) Based on the isotropic unit cell, the method of designing the surface wave Fourier-transformation lens verified in the experiment is presented. Under the multi-feed excitations, the surface plane wave with different radiate directions in two-dimension plane can be accomplished.3) Combining the metasurfaces with the theory of the holographic leaky-wave, the new multi-beam antennas by respectively using the whole-area and sub-area methods of generating the impedance holograms are realized. And based on the whole-area method of generating the hologram, there is the phenomenon called "rabbit’s ear" in generating the double-beam radiation. The side-feed method is presented to solve the problem and that is verified in the experiment. Combining with the theory of leaky-wave antenna, the analysis of equivalence between the one-dimension holographic antenna and the leaky-wave antenna is discussed, and then, that is extended to the two-dimension circumstance. The important phenomenon that the beam can scan in two-dimension space only by the controlling of frequency is firstly discovered in this area. And the experiential calculating formulas of the two-dimension beam scanning angle are given.4) Based on the textures of spoof surface plasmon polaritons, combining with the theory of holographic antenna, the spiral hologram is generated. The metasurface has no grounded metal, so it can realize the right-hand and left-hand electromagnetic radiations in the positive and negative directions of the surface respectively.5) By using the isotropic textures, two new devices with dual-function are designed. The first device can realize the double-direction radiation under the same polarization. The second device can realize the single-direction radiation under the orthotropic polarization. The two devices have the different performances of frequency scanning under the different polarization excitations. For the horizontal polarization, the beam can complete the one-dimension spatial frequency scanning. And for the vertical polarization, the beam can complete the two-dimension spatial frequency scanning. And in this dissertation, the performance of one-dimension spatial frequency scanning of the first dual-functional device is experimently verified.6) Combining the method of surface wave lens with holographic leaky-wave antenna, the method of realizing the low-profile antenna system is presented. The lens can be considered as the feed network and the holographic impedance textures can be considered as the modulator of radiation. At last, based on the different feed points with frequency agility, the radiate beams generated by the antenna system can cover the two-dimension space. The simulate and the near-field measurement results can verify the validity of the antenna system.7) Based on the hybrid isotropic and anisotropic textures, the dual-sensor "cross" type antenna is proposed. The antenna can realize the independently beam scanning with frequency in two orthotropic dimensions. Based on completely illuminating on the object by the antenna, by using the signal processing method of single-radar, the microwave image system based on the "cross" type antenna is realized. The images under the different circumstances of Signal to Noise are reconstructed in the simulation and the good image resolution is acquired. And also the image system has the good performance of the anti- noise.