| With the development of mobile communication technology,smart devices tend to be smaller in size and diverse in function.Antenna is an essential part of modern intelligent equipment.Its function is to convert radio frequency signals into electromagnetic waves and launch them into space.Therefore,in order to adapt to the trend of miniaturization of smart devices,new requirements for antenna design have been put forward.Small size,low cost,wide band and anti-interference antennas will be the future direction of small antenna development.As an important member of the antenna family,microstrip printed antennas have entered into people's vision because of their small size,light weight,low cost and easy integration in the circuit.In February 2002,FCC approved UWB technology for civilian use.According to the Federal Communications Commission(FCC),the band from 3.1 to 10.6GHz will be used as a range of UWB Systems[1].From then the research of ultra wideband antenna has become the focus of current research.In order to meet the miniaturization trend of modem communication equipment,UWB wireless technology is becoming more and more important as a new wireless communication technology.Considering the early ultra wideband antenna size problem,now the UWB antenna design requires not only the antenna has the advantages of small volume,good radiation efficiency,to cover all features,at the same time should be avoided and other communication systems interfere with each other.Uwb communication system,however,the working frequency band covers narrowband communication systems of the other frequencies,such as wireless local area network(WLAN)spectrum(5.15?5.85 GHz),and satellite communication system x-band(7.25?7.75 GHz)frequencies,the existence of wireless communication system will interfere with ultra-wideband antenna work.In order to reduce these interferences,a resonant structure can be introduced into the ultra wideband antenna to realize the filtering function of ultra wideband antenna.This thesis is based on the ultra-broadband monopole antenna,which is used to realize the function of filtering by introducing a resonant structure around the feeder.The new filter antenna uses taconic-RF35 material,has dual-band notch characteristics in 5.5GHz and 7.5GHz,and two notch points at center frequencies of 5.5GHz and 7.5GHz can be independently adjusted.The first paragraph of this design is based on the structure of type E resonant ultra-wideband filter antenna pattern bandwidth ranges from 3.5 to 10.5 GHz(VSWR<2),on the basis of meet the ultra-wideband antenna performance achieved dual band-notch function 5.5 GHz(5.23?5.82 GHz)and 7.5 GHz(7.35?7.85 GHz).In the antenna radiation plate,the effect of the double U slit in the structure of E type metal is to create a double resistance band,which avoids interference with other communication systems.On the basis of experiments,a large number of simulation experiments are carried out to obtain the specific structural parameters of the antenna.The second paragraph of the antenna is ultra-wideband filter based on CSRR loaded antenna,the antenna in the 3.2 GHz to 8 GHz frequency range,return loss is less than-10 db,and in the center frequency 3.5 GHz(WIMAX),and 6.2 GHz(C band)satellite communication,stopband effect obviously.Ultra wideband filtering methods currently used by most of the antenna areslotted in the radiation patch to realize the filtering effect,and the main innovation of this paper is through introducing a resonant microstrip feeder structure,to achieve filtering effect. |
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