| Metamaterials has been shown to exhibit electromagnetic properties not attainable with naturally occurring materials which is artificially engineered composites. The use of such materials has been proposed for numerous applications at microwave frequencies. Miniaturized microwave components have drawn increased attention due to the size shrinking of the modern communication systems. Antenna is an important part of the wireless communication system which will affect the performance of the whole system directly; the microstrip antenna is an important branch in the antenna field. Metamaterial-based antennas have been extensively studied in recent years, mainly with the goal of reducing their overall size without sacrificing the other relevant radiation properties. This thesis work focuses mostly on studying different potential applications of meta-transmission line(TL). This paper studies the application of metamaterial research and performance in the field of microstrip antennas, including metamaterial loaded monopole microstrip antenna and composite right/left handed(CRLH) leaky wave antenna in two parts.Firstly, the cultural backgrounds of Metamaterials were systematic elaborated at the first two chapters, then based on what the theory of composite right/left handed(CRLH) transmission line(TL) was introduced. Then, the novel complementary split-ring resonators(CSRRs) proposed in this thesis was etched on the top surface of traditional rectangular microstrip antenna to achieve an ultra-wideband, high gain patch antenna. It can be found that this antenna has strong radiation in the horizontal directions for some specific applications when it comes to the radiation pattern. For comparison, the traditional and transformational structures loaded on the patch antenna were researched separately. By comparison, the microstrip patch antenna can decrease 35.4% in size which was loaded with the novel complementary split ring resonator(CSRRs) structure proposed in this thesis, this is a good performance compared with the other structures. Operating bandwidth covers from 4.8GHz to 8.23 GHz which can reach 52.65% relative bandwidth.Finally, as a generalized model for Left Handed Materials(LHM) transmission line(TL), composite right/left handed(CRLH) transmission line(TL) provides very unique phase response, such as dual-band operation, bandwidth enhancement, nonlinear dependence of the frequency, and the existence of critical frequency with zero phase velocity. Then, leaky wave antennas based on a simple composite right/left handed(CRLH) transmission line(TL) structure which was propsed in the thesis were studied. Leaky wave antennas based on substrate integrated waveguide were designed by etching the structure on the surface of transmission line. Finally two one-dimensional leaky wave antennas which have good electrical properties and good performance in the beam scanning were proposed in the in the fifth chapter. The first one etching graded interdigital structures on the upper surface that it can only achieve a radiation on the single side, while the other one etching interdigital structures on the both surface to realize a radiation on the two sides. |
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