| The past two decades, EBG(Electromagnetic Band Gap, EBG) structure as a new periodically artificial materials, depending on its unique electromagnetic properties, has caused a strong concern of scholars from all over the world. The most significant features of EBG structure is that electromagnetic waves can not propagate in a certain band,where forms a band gap. Based on this nuture, EBG structures are widely used in the fields of microwave and antennas. High-impedance surface is a kind of dimesional EBG structures with dielectric-metal mixture, which can present high impedance and in-phase reflection in a certain frequency range. High-impedance surface is applied in antenna design. It not only improves the radiation efficiency and the radiation pattern of the antenna effectively, but also reduces the the profile section of the antenna system, which has meet the development requirement of modern communication equipment miniaturization. This paper mainly studies the application of the high-impedance surface in low profile antenna. The main work can be summarized as follows:Firstly, the study begins with the reflection characteristics of the high-impedance surface. Then, the simulation model for reflection phase of the high-impedance surface is established with electromagnetic simulation software Ansoft HFSS, to analyze the effects on the reflection phase of high-impedance surface when changes the unit parameters. The reflection phase is observed when the angle of incident wave is changed under TE mode and TM mode.Secondly, the application of the high-impedance reflector in low profile dipole antenna is studied. In the design process of dipole antenna reflector, the effects on antenna radiation by changing the number of the patches are analyzed. Then, it discusses the variation of the antenna gain and return loss when the distance between antenna and the reflector is changed. The results show that the high-impedance reflector can achieve better gain and return loss when the reflector is very close to antenna. Compared with metal reflector, the high-impedance reflector can reduce the profile of the antenna obviously.Finally, the paper studies cylindrical high-impedance surface based on the high-impedance plane reflector. A group of cylindrical high-impedance surface with 6 units is designed. It makes a detailed analysis of the impact on antenna radiation when the radian and the curvature radius of the cylindrical reflector are changed. The simulation shows that the cylindrical high-impedance reflector with ?3/2 radian has a preferable reflection characteristics when the reflector is close to antenna. It proved the cylindrical reflector can increase the gain and the radiation efficiency of the antenna and saves the materials, which can reduced the profile of antenna greatly. |
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