| Ultra wideband(UWB) antenna has got much attention in the academic and industrial fields as a crucial component of the ultra-wideband system. In order to avoid the interference between the narrow-band communication systems and UWB, such as WiMAX and WLAN, the UWB antenna must have the stopband band in the interference band, which is called notch characteristic. But the traditional notch has poor selectivity that is hard to achieve the purpose of eliminating impact. So designing the UWB notch antenna with high rectangular coefficient has extremely important value.Based on the research of high rectangular coefficient of UWB band-notch antenna, the thesis has completed the work in the following areas:(1) The background and significance of the thesis is summarized; thesis of UWB technology is briefly outlined, including the definition, advantages and limitations; the history and development of notch-band UWB antenna research are introduced; the various important parameters of the antenna.(2) Based on the mixed notch-method that two first-order notches become a two-order notch by the traditional coupling, and the two symmetrical transmission poles are introduced, three high degree of rectangular radio of notch-band UWB antenna are proposed. The first antenna has got 5.0-5.6GHz notch-band by etching a half U-shaped slot on the radiating patch, and parasitic stub near the slot in the floor. The rectangular ratio is 0.6. The other antenna has got the 5.0-6.0GHz notch band by etching symmetrical discounted slots parasitic on the floor, while keeping the parasitic stub near the slot in the floor. The rectangular ratio is 0.75. The last antenna using asymmetric coplanar waveguide(ACS) feed achieves antenna miniaturization. The size reduces 50% and the bandwidth is 2.3-11.2GHz which includes the Bluetooth and the UWB band. Meanwhile the antenna obtains 2.8-3.8GHz and 5.0-5.9GHz notch band whose rectangular 0.6.(3) Based on the designed theory of stopband filter, a UWB filter antenna is designed, which the two-stage band-stop filter is loaded to the UWB bow-type planar antenna. Stopband filter is consisted of a quarter shorted wide open and coupling strips which includes open and short strips. The rectangular ratio and bandwidth of notch are controlled by adjusting the electrical length of the open stubs because the transmission poles of the band-stop filter may change. The notch band of antenna is 5.1-6GHz and the rectangular ratio is 0.75, and the optimum notch result is-2.3dB.(4) A notch ultra-wideband MIMO antenna with high rectangular coefficient is designed through combining the UWB and MIMO. Antenna has polarization diversity mode. Two open stubs extending from the floor can expand the bandwidth, improving the isolation between ports the same time. The antenna bandwidth is 2.8-10.8GHz. Etching SRR slots in the radiating patch and polygonal slot on the floor produce 5.2-5.9GHz notch band. The rectangular ratio is 0.7. The isolation is more than 20 dB, and radiation pattern is orthogonal. |
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