Design Of Filtering Antenna And Filtering Power Divider For DCS/WLAN

With the amazed development of modern wireless communication technology,Digital Cellular System(DCS),Wireless Local Area Network(WLAN)and other wireless communication technology are in the evolution of mutual integration,continuous innovation,and the miniaturization of terminal device is required more and more high.A variety of devices are integrated design together,so that a device has the functions of a variety of devices,can not only guarantee even improve its original performance,but also reduce the size of device effectively,reduce the loss of circuit,restrain the interference of noise and improve the quality of communication,therefore,it has wide application prospect.Antenna,power divider and filter are the key components of RF front end in DCS and WLAN communication systems,therefore,it has been of great theoretical value and practical significance to study the DCS/WLAN filtering antenna and filtering power divider which integrates the functions of antenna,power divider and filter.Two filtering antennas were designed in this paper,the first was the directional filtering antenna applied in WLAN system,the design method was that antenna and filter structure were designed on different layers,a microstrip antenna with aperture coupled feeding structure was designed at first,and then the filtering structure of four order resonator with cross coupling was introduced in feeder,thus the antenna with filtering function was realized;The second was omnidirectional dual frequency filtering antenna applied in DCS and WLAN system,the design method was that broadband antenna and dual frequency filtering structure were integrated design together,broadband printed monopole antenna was designed to meet the requirement of bandwidth at first,and then the structure of dual frequency filtering structure was composed of two similar dual mode resonator and feed connector of T type,finally the feeder of broadband antenna was replaced by dual frequency filtering structure,thus the antenna with dual filtering function was realized.Two filtering power dividers were designed in this paper,the first was the filtering power divider applied in WLAN system,hairpin resonator with two order coupling was used to achieve two same bandpass filter at first,then two-way filters were paralleled by increasing the length of the microstrip line in the input port of each filter,finally distributed isolation network was introduced between two-way microstrip lines to improve isolation,thus the power divider with filtering function was realized;The second was the dual frequency filtering power applied in DCS and WLAN system,the broadband power divider that bandwidth to meet requirement was realized based on the improvement of Gysel power divider,and then,the SIR stub was loaded in open resonant cavity of SIR and the dual frequency structure was realized by electrical coupling,finally this structure and broadband power divider were integrated design together,thus the power divider with dual frequency filtering function was realized.In this paper,the structures were designed according to theoretical knowledge and parameters were simulated and optimized by electromagnetic software of HFSS13.0,the four devices were processed and measured after obtaining the standard result,the measured results show that the gain of the directional filtering antenna is 5.28dBi,the gain of the omnidirectional dual frequency filtering antenna is 2.29dBi in DCS frequency band and 2.62dBi in WLAN frequency band;The two filtering power dividers have the return loss more than 10dB and isolation more than 20dB in passband,and have good filtering characteristic and power distribution characteristic,therefore,the filtering antenna and the filtering power divider are designed in this paper meet design requirement basically.