Ultra Broadband Radiation Characteristics Of Reflector Antenna System Research

In this dissertation, i have simulated the radiation characteristics of UWB reflector antenna with different parameters according to the theoretics. The purpose is to find the relationship of the result and the parameters. We get an optimization of the antenna's design in the end.There are many differences between the traditional narrow band antenna and the UWB antenna, the most important lies in the signal which they radiate. The UWB antenna radiates short impulse signal in nanosecond when the narrow band antenna radiates harmonious signals.Today the research of the narrow band antenna is mature, but the description methods of it isn't appropriate to the UWB antenna any more. As the spectrum of the UWB antenna's signal is wide, we should study it in the view of time domain. But the research of it is under development, there isn't uniform cognition of it at present.At first, the dissertation introduces the background and significance of the UWB reflector antenna's research. Then we show the development of the antenna. We also introduce the essential conception of the antenna.In the following chapter, we introduce the basic theory of the TEM born antenna and simulate the radiation patterns of TEM horn in different parameters. The results of the simulation shows that the radiation energy of the TEM horn mainly focus on the main axis, there are great relationship between the parameters of the antenna and the radiation pattern.Then we add some proper UWB reflector antennas in the models which have been used in the last chapter and simulate them. From the datas and figure we get, we find that the radiation pattern of the TEM horn can't match up with the reflector as the phase center of the TEM horn is uncertain and when the TEM horn move along the central axis, the field of the reflector's surface changes, this leads to the change of the far-field radiation. At the same time, the effect of the TEM horn's shade is not neglectable.Actually, no matter what we do is to optimize the structure of the antennas and get a optimization of the system design. So we introduce the stochastic optimization algorithms in chapter 5. We use the CST to transfer the programme of evolutional algorithms to optimize the reflector antenna. Finally, we summarize the work of this dissertation and predicte the next research directions.