Research And Design Of Ka-band Broadband Circularly Polarized Microstrip Array Antenna

Microstrip antennas have the advantages of light weight,small profile and low cost.While millimeter wave combines the characteristics of both microwave and infrared waves.Therefore,the millimeter-wave microstrip antenna has been widely used in the fields of satellite remote sensing,detection guidance,and fuze systems.This paper is based on the millimeter wave microstrip antenna project requirements,three microstrip array antennas are investigated at Ka-band.The first one is 4×4 broadband caliber coupling array antenna.The second one is 4×4 broadband circular polarized array antenna.The last one is 8 x 8 circularly polarized phased array antenna.Firstly,the basics and design principles of the antenna are introduced.Then,the basics and design principles of the antenna are introduced.This will provides the theoretical basis for designing array antennas below.Secondly,the method of extending the bandwidth of the microstrip antenna is studied,and a 4 x 4 array antenna with 8 mm band is designed.The bandwidth is expanded by using the aperture coupling feed.The simulation results show that the gain at the center frequency of 35GHz reaches 18dB,and the bandwidth of S11<-10dB reaches 17.1%.Thirdly,the principle of circular polarization of the microstrip antenna is studied.In view of the advantages of the circular patch,a circular patch is first proposed to replace the traditional rectangular patch as a circular polarization patch unit.Finally,a 16-port equal amplitude phase splitter is formed to form a 90 ° phase difference between adjacent units,and a 4 x 4 circularly polarized microstrip array antenna is completed.Simulation results show that the left-handed circularly polarized gain reaches 18dB at 35GHz and the axial ratio bandwidth reaches 3GHz,and the bandwidth of S11<-10dB reaches 17%.The antenna axis ratio in the main lobe width is less than 3dB.Finally,The principle of array antenna beam scanning is studied.An 8 x 8 circularly polarized phased array antenna is designed by the continuous phase rotation method.The simulation results show that the gain of the center frequency of 35GHz is more than 20dB and the half-power beamwidth is less than 9 °.The antenna beam can be scanned ± 30 ° pitch angle,the antenna axis ratio in the main lobe width is less than 3dB.