Research On Multi-frequency Circularly Polarized And Microstrip Filtering Antenna

In recent years,the development of the intelligent transportation system has improved people's traffic conditions with traffic jams,and reduced traffic accidents.With the rapid development of intelligent transportation systems,the demand for on-board equipment is increasing,and the performance are getting higher.The first part of this paper focuses on the research of multi-frequency circularly polarized vehicle-mounted antennas used in intelligent transportation systems.With the development of wireless communication systems toward multi-band and multi-standard,the RF front-end systems needs to integrate a lot of antennas and filters,which results in the RF front-end system becoming larger.Antennas and filters are two indispensable devices for RF front-ends.In recent years,more and more researches have been conducted on their integrated designs.However,most filtering antenna research focuses on the filtering performance.There are few studies on circularly polarized and dual-polarized filtering antennas.Therefore,the second part of this paper mainly focuses on the research of the filtering antenna with circular polarization and dual polarization performance.The work in this article mainly includes the following parts:(1)In response to the demand for multi-frequency circular polarization of on-board antennas,a miniaturized dual-frequency dual-circular polarized antenna for GPS and DSRC systems is proposed.The antenna operates in the L1 frequency band of the GPS and achieves right-hand circularly polarized radiation,and works in the DSRC frequency band to achieve left-hand circularly polarized radiation.And the antenna size meets the requirements for miniaturization.Finally,on the basis of simulation and optimization,the proposed antenna was prototyped and measured.The test and simulation results are in good agreement and meet the design goals proposed in the article.(2)Based on the research of circularly polarized antennas,aiming at the research progress of current filtering antennas,a filtering antenna with circular polarization performance is proposed.The first is the design of the antenna feeding network.The feeding network integrates phase shifting,filtering and power distribution,and outputs two equal amplitude,quadrature signals with a phase difference of 90° at the output port.The feed network feeds the upper radiating patch through the probe,achieving circular polarization performance.Finally,on the basis of simulation optimization,the proposed antenna was prototyped and measured,the test and simulation results are in good agreement.(3)At present,there are not many researches on dual-polarization filter antennas.In this paper,a filter antenna with ±45° dual polarization characteristics is designed.This antenna feed network consists of two half-wavelength resonators and is coupled via a ring slot in the floor to achieve filtering characteristics.And the two groups of feed networks are perpendicular to each other to achieve dual polarization characteristics.The antenna has a filtering characteristic,flat in-band gain,and obvious out-of-band filtering performance,and the antenna has a dualpolarization characteristic of ±45°.It can meet the application scenarios of dual-polarized antenna requirements.Finally,the proposed antenna was prototyped and measured,the test and simulation results are in good agreement.