Design And Research Of Miniaturized UWB Antennas With Band-notched Characteristics

The demand for miniaturization and portability of wireless communication devices has prompted the development of antennas toward miniaturization and integration.Ultra-wideband?UWB?technology is widely used in wireless communications because of its high speed,low power consumption,and strong anti-jamming ability.To realize the integration of UWB antennas and systems,UWB antennas should have characteristics of small size and low profile.In addition,there are many narrowband communication bands included in UWB band.To inhibit their interference to UWB communication systems,UWB antennas should also have band-notched functions.Based on the requirements above,the main research and innovation work are listed as follows:First,a beehive fractal UWB antenna with dual band-notched property is presented.The excellent UWB performance is achieved by using the second order beehive structure as radiation patch and the defected ground structure.The dual band-notched characteristics at 3.27⁴.27GHz and 7.2⁸GHz are achieved by embedding hexagon and rectangle wide gaps and adding two symmetrical fishhook shape stubs on the radiation patch and etching a narrow inverted U-shaped slot on the feeder line.It can efficiently restrain the interference of WiMAX,C band satellite and X band satellite narrowband systems.Then,a nested iterative fractal UWB antenna with triple band-notched characteristics is proposed.The excellent UWB characteristic is obtained by using the third order Sierpinski like fractal structure as radiation patch composed of circular and regular hexagon through nested iteration and improving ground-plane shape.The triple band-notched characteristics at3.1³.8GHz,5⁵.9GHz and 7.2⁸GHz are produced by adding two symmetrical L-shaped open stubs on both sides of the feeder line and etching a narrow U-shaped slot with different size on the ground-plane and feeder line respectively.It can efficiently rejects the jamming of WiMAX,WLAN and X band satellite narrowband systems.Finally,a circular monopole UWB antenna with multi-band-notched characteristics is proposed.The excellent UWB characteristics is achieved by using a circular patch as the radiator and optimizing the ground-plan structure.The band-notched characteristics of triple stop-bands at 3.2³.8GHz,4.5⁵.5GHz,7.2⁸.6GHz are achieved by embedding two arc U-shaped slots on the radiation patch and etching a narrow U-shaped slot on the ground plane.It can effectively filter out interference from WiMAX,large capacity microwave communication,partial WLAN,X band and ITU 8GHz narrowband systems.Processed and tested three antennas.Simulated and measured results show that three antennas all achieve S₁₁>-5dB or VSWR>7 in the reject-bands,which produced excellent band-notched characteristics.In the pass-bands,the peak gains of the three antennas are all above 3dBi,the transmission coefficients are less than-30dB,the group delay are also kept within 2ns and omnidirectional radiation are maintained.Three antennas have favorable frequency domain and time domain characteristics,which are all suitable for actual UWB communication systems.The paper has 64 figures,9tables and 80 references.