| With the rapid development of the wireless communications industry, as the air wireless signal interface, the antenna is more and more important in the wireless communication system. The pace of progress has brought challenges to the antenna, and wireless applications in the future will require the antenna with higher performance. The antenna is developing towards miniaturization, multi-frequency, and high-gain. There are still varieties of deficiencies of Traditional microstrip antenna, such as the low-gain, narrowband, and low efficiency, limiting its application. Therefore the further study is to improve the performance of the antenna.Metamaterials, one of the artificial magnetic materials, are the periodic or non-periodic structures. Its nature not only depends on the constituent material’s chemical properties, but also the structure of the constituent units. Metamaterials can realize arbitrary design where the dielectric constant or magnetic permeability is in the positive or negative range, such as the negative dielectric constant and the magnetic permeability of the left-handed material, which conventional materials can not achieve. Also metamaterials contains a large number of novel physical phenomena, such as inverse Snell’s law. As a transmission line implementation form of the metamaterials, composite right/left-handed transmission line (CRLH-TL) has both left-handed and right-handed nature of metamaterials’. It makes up for the shortcomings of the traditional resonant metamaterials, and the bandwidth and loss are far much better than the left-handed materials. To use the unique characteristics of the composite right/left-handed transmission line for the design of multi-frequency, high-gain antenna can bring new method. In this article, we study the theory of metamaterials firstly, especially the composite right/left-handed transmission line theory, and later we design two antennas based on CRLH-TL structure.After summarized the common technique of multi-frequency antenna, we also designed the multi-frequency and miniaturized microstrip antenna based on two-dimensional composite right/left-handed transmission line mushroom type structure. The mushroom-like structure and the blending line can generate multi-resonant frequency. The surface current distribution and other parameters were simulated to analyze the resonance characteristics of the antenna. Otherwise we fabricated the antenna samples, and compared the simulation and measured results. The antenna can work at four bands of2.62GHz,3.91GHz,6.52GHz and8.05GHz. Meanwhile, the simulation results show that the antenna resonance performances at the resonant frequency are basically consistent. This antenna can meet wireless communication applications.In the thesis, we designed a novel, no porous antenna based on unit structure of the composite right/left-handed transmission line. The defected ground structure which the antenna loaded with and the radiation patch above can produce high radiation energy jointly. Additionally, we establish the equivalent circuit model of the antenna structure. By changing the parameters of the equivalent model, we can adjust the resonant frequency of the antenna. Then we fabricated the antenna and test it. The comparison of simulation and experimental results demonstrates they are in good agreement with each other, and this can prove the correctness of the equivalent model. The maximum measured gain of the antenna in the center frequency is6.7dBi, and the highest measured radiation efficiency is75.6%. In addition, we also preliminary study a1×2array antenna composed of the proposed antenna. |
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