| The ultra-wideband communication technology is a novel wireless communication technology which transmits signals with short pulse, and usually the pulse can cover a very wide frequency band .As a result, the ultra-wideband antenna must be able to radiate and receive the short pulse signals without distortion, in other words, the ultra-wideband antenna has to own several octave impedance bandwidth or more, and stable phase center, which enables the ultra-wideband antenna to transmit and receive short pulse signals without distortion.The ultra-wideband antenna which based on wide slot structure is a kind of miniaturized and easy-feed ultra-wideband antenna .The ultra-wideband antenna has not only the extremely wide band in frequency domain ,but also stable phase center ,which makes the antenna radiate and receive the short pulse signals without any distortion ,and suitable for various ultra-wideband communication systems.Firstly, some basic conception about the ultra-wideband antenna are introduced, including several performance parameters .And an expatiation on the structure types of the ultra-wideband antenna are given .Analyzing the electromagnetism theory of the antennas .Also, the Finite Element theory is introduced.Secondly, the impedance and radiation properties of the ultra-wideband antenna are thoroughly analyzed. The return loss S11 curve of the antenna and the E plane and H plane pattern in two frequencies are given. And discussing the antenna size's effect on the impedance bandwidth. Introducing a new method to improve the capability of the antenna. The application of this method on some antennas proves the practicability of this new method.At last, two ultra-wideband antennas are designed .Though the simulation with HFSS, several performance parameters are given. The effects that the antenna sizes changed are analyzed with the S11 curve. The current distributing is presented. The reason of effect is explained after analyzing the curve. |
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