| Ultrawide band positioning system has a huge advantage in that it can precisely position in complex environments, so it has been more and more popular academic circles and market. Ultra-wideband antennas shoulder the communication task as the core component of UWB positioning system and affects the quality of system.Firstly, this paper introduced the UWB positioning system and analyzed the UWB positioning system to proposing the requirement of antenna. This paper also proposed two methods to obtain receive waveform.Secondly, In this paper, a compact Vivaldi antenna with triple notch band is designed. Three SIR structures are introduced into the Vivaldi antenna to creating band-notched of 3.3 GHz-3.8 GHz for WIMAX and 5.15 GHz-5.35 GHz, 5.725 GHz-5.825 GHz for WLAN. In order to effectively mitigate the undesirable interferences generated from different enviorment, an UWB Vivaldi antenna with switchable and widely tunable Band-notch Characteristic is proposed. The antenna proposed in this paper bases on a tranditional microstrip-fed Vivaldi antenna, One SIR are inserted to obtain notched band. Tunable band notch is achieved by loading varactor diodes. With the changing of DC bias voltage, the center frequency of notched band changes from 3.1 GHz to 6.8 GHz. Through rational parameters design, the center frequency of notched band is out of UWB range when the DC bias voltage of the varactor diode is 0 V. The band notch is on off state. The switchable band notch characteristic is obtained.Finally, according to the application requirements of a UWB antenna with low profile is designed. The proposed antenna is printed on a dielectric plate,and it has overcome the disadvantages of weight and fabrication. By top loading and shorting, the antenna height can be reduced. The antenna proposed in this paper has an overall height of 6 mm and relatively height of 0.050λ, where is the minimum operating wavelength. |
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