Research On Several Electromagnetic Properties Of Metamaterial And Their Applications

This dissertation mainly works on the properties and potential applications of Metamaterial.The first part of this dissertation (chapter 2) investigates the subwavelength resonance and radiation properties of Metamaterial, and the applications of resonator and frequency steering antenna. First, the interaction between Metamaterial slab and traditional slab is analyzed. It is verified that the resonant frequency of adjacent Metamaterial and traditional slab is only related to the ratio of thicknesses of the two layers, while has no relation with the whole thickness, so it is possible to realize subwavelength resonator. The coupling characteristic between Metamaterial slab and traditional slab is calculated using coupling mode equations to obtain the resonant condition. The radiation properties of dispersive anisotropic Metamaterial slab with embedded current source is finally analyzed, it is found that directive radiation is achievable near the frequency of zero effective refractive index, for the dispersive characteristic, the output radiation angle is different at different frequencies, like the rainbow phenomenon in visible light regime, and frequency steering antenna is realized in simulation and experiment.In the second part, the dissertation (chapter 3) works on tunable refractive index Metamaterial and its applications in voltage controlled steering antenna. By embedding varactor into passive Metamaterial, the effective refractive index can be controlled by bias voltage. As a result, the output phase from the Metamaterial slab can be adjusted by tuning the effective refractive index through bias voltage, and the radiation angle can also be controlled. In experiment, voltage controlled steering antenna is realized at 4.95 GHz with a scanning range of±30°, the half power beam width (HPBW) is 6.5°, the radiation gain is 8 dBi.The third part of this dissertation (chapter 4) studies active Metamaterial embedded with negative resistance and gain element. By embedding tunnel diode with negative resistance into composite right/left-handed transmission line (CRLH), active CRLH is realized in microwave regime, which verifies the possibility of compensating loss in negative refractive index (NRI) Metamaterial by active element with positive gain. Active Metamaterial is also experimentally implemented for subwavelength metallic structure with amplifying elements. Active Metamaterial of subwavelength metallic structure is implemented with embedded monolithic amplifying element, and is verified in experiment.The final part of the dissertation (chapter 5) investigates the waveguide mechanism based on spoof surface plasmon polaritons (SPPs). The one and two dimensional periodic corrugated metal surfaces are verified theoretically with modal expansion method to support spoof SPPs. By designing the geometric parameters, the spoof SPPs can be achieved at any frequency band. A U-V shaped channel on metal surface is found to behave as the spoof SPPs, and the electromagnetic (EM) field is highly localized at the bottom of the groove. With subwavelength modal area and several hundred wavelength propagation length, this kind of the spoof SPPs is found to be an excellent candidate of the waveguide, especially in the application of 90°sharp bend transmission.This dissertation proposes some novel applications of subwavelength resonator, directive antenna, frequency steering antenna and voltage controlled steering antenna, utilizing the unique properties of Metamaterial. To solve the problem of low loss and narrow band in Metamaterial, active Metamaterial with embedded negative resistance is put forward and realized. Finally, a novel corrugated channel on metal surface based on spoof SPPs is experimentally implemented and found to support high transmission.