| Ultra-Wideband(UWB)communication technology is widely used in many communication scenarios by virtue of its high rate,low cost,good confidentiality,high penetration capability and ultra-wide bandwidth.As an important component of UWB communication system,antenna has a great impact on the performance of UWB system.However,in the UWB communication band(3.1-10.6GHz),there are narrowband bands such as Wireless Local Area Network(WLAN),International Telecommunication Union(ITU),Xband signals and Worldwide Interoperability for Microwave Access(Wi MAX),etc.In order to filter these narrowband bands without increasing the complexity of the system,it is necessary to start from the structure of the antenna itself and design the antenna with band-notched characteristics.This paper focuses on the following parts of the UWB antenna and its band-notched characteristics,and do the following researches:Firstly,the UWB antenna is studied.Based on the fractal principle,an UWB antenna with fractal structure radiating patch is designed,and the operating bandwidth is 1.6-20.6GHz with good radiation characteristics.Then a novel UWB monopole antenna is designed,which consists of a circular radiating patch with a hexagonal slot in the middle and a defective ground structure,with an operating bandwidth of 2-28.6GHz and a size of only 25mm×14mm×0.7mm,which has the advantages of miniaturization and wide bandwidth.The second ultra-wideband antenna is improved,and the improved antenna has a bandwidth of 3.4-23.8GHz,which is easier to add multiple notch structures.The antennas are all fed by microstrip line.Then the band-notched characteristics of the antenna are investigated.The U-shaped slot is etched on the microstrip line of the fractal ultra-wideband antenna,which is adjusted and optimized to finally avoid the interference of the ITU band to the UWB system in the frequency band of 1.6-20.6GHz;the slot structure is etched on the radiating patch of the improved novel structure UWB antenna to achieve the band-notched characteristic in the Wi MAX band with the antenna operating bandwidth of 3-23.8GHz;Based on the step-shaped antenna proposed by predecessor,the U-shaped slot is loaded on the patch,and the WLAN band is effectively filtered in the working band of 3.1-10.7GHz.Then,the performance of the three single bandnotched antennas is analyzed.Finally,the antennas are multi-band-notched processed.Considering the interference of narrowband signals in Wi MAX band,WLAN band,X-band and ITU band to the UWB system,two dual band-notched UWB antennas and two triple band-notched UWB antennas are designed on the basis of three single band-notched UWB antennas,respectively. |
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