Research On The UWB Antenna With Band-Notched Characteristic

Ultra-wide-band(UWB)antenna has drawn significant attention for its simple structure,easy integration and high anti-interference in recent years.After Federal Communications Commission(FCC)distributing 3.1-10.6 GHz to UWB antenna for commercial use,UWB antenna designs have made great progress.However,there are overlaps between UWB bands and existing narrow communication bands,such as Worldwide Interoperability for Microwave Access antenna system(WiMAX,3.3-3.7 GHz)and Wireless Local Area Networks(WLAN,5.15-5.35 GHz,5,725-5.825 GHz),which can produce interference to UWB antenna systems.Accordingly,the main work in the paper are as follows:(1)The development history and research status at home and abroad are introduced in order to understand the UWB antenna clearly.Based on basic theory of antrnnas,two numerical methods of antenna,moment of method(MOM),finite difference time domain method(FDTD)and finite element method(FEM),are emphatically deduced.In view of the fact that all the simulations in this paper are implemented by HFSS software,a brief introduction to HFSS software are also given.(2)Dual band-nootched UWB antenna is presented in the paper to suppress inteferences from WiMAX and WLAN.The microstrip-fed antenna structure is improved and the frequency band is broadened by cutting rectangle-shaped slot in the radiation patch and triangle-shaped slot in the metal ground.Based on the improved UWB antenna,the dual band-notched characteristic at WiMAX and WLAN bands is achieved by adding an arc-shaped strip on the ground and etching an U-shaped slot in the radiation patch.The simulated and measured results show that the VSWR on the 3.34-3.78 GHz and 5.1 9-5.89 GHz is upper than 2.Meanwhile,the E-plane pattern of the antenna is similar to the dumbbell-shape,and the H-plane pattern has better omnidirectionality.The peak gain achieved at 8 GHz is 3.5 dBi.(3)The proposed dual band-notched UWB antenna avoid entire 5.2-5.8 GHz frequencies bands to suppress WLAN signal,which do disspated bands at 5.35-5.725 GHz.First of all,a novel triple band-notched UWB antenna is proposed to avoid signals at 3.3-3.7 GHz,5.15-5.35 GHz and 5.735-5.825 GHz.Based on traditional CPW-fed antenna,a rectangle-shaped slot is etched in the semi-circle-shaped radiated patch to reduce antenna's size.The dual band-notched characteristic at upper WLAN frequency bands and lower WLAN frequency bands is realized by adding two quarter-wave length strips on the radiated patch of the UWB antenna.By adding two quarter-wavelength rectangle strips on the radiation patch and etching half-wavelength hook-shaped slot on the ground,the triple band-notched characteristic is achieved.The simulated and measured results show that the VSWR is upper than 2 at 3.05-3.85 GHz,4.98-5.36 GHz and 5.58-5.94 GHz bands,and the radiation patterns are similar to monopole antenna's patterns.At the same time,the peak gain achieved at 6.5GHz is up to 3 dBi.