The Design Of A Dual Circularly Polarized Microstrip Antenna Array

At the moment,the information age of human life is undergoing enormous changes.With the rapid development of wireless communication technology,the arrival of mobile communications 4G era has further promoted the development of wireless communication technology.As one of the most important parts of the wireless communication system,the antenna has been developed rapidly.For quite a long time,the traditional simple antenna has been playing a stabilizing role in serving the wireless communication system.However,in recent years,due to the special requirements of the antenna platform,the traditional single polarization antenna can not meet the actual requirements.Circularly polarized antennas have attracted more and more attention.Currently,the research topics of circularly polarized microstrip antennas include high gain circularly polarized antennas,dual circularly polarized microstrip antennas and broadband circularly polarized microstrip antennas.In this paper,a compact sum and difference network with high isolation for single pulse antenna system and a dual circularly polarized microstrip antenna array for monopulse antenna system are studied.The main contents are as follows:1 A high isolation 180 degree hybrid network was designed,the network has a higher isolation than the traditional circular 180 degree hybrid network.It can achieve a two-way signal's sum and difference operations.A three branch line coupler and a four branch line coupler was designed.At the same time,a 90 degree delay line and a broadband two way power divider was designed.They consists of a 7-Port compact sum and difference network.The network can achieve four signals' three kinds of difference operation.The physical test results show that the network is good and can be used further.2 A microstrip antenna unit with dual circular polarization was designed.The unit use a double feed network with coplanar microstrip line to achieve dual circular polarization.The simulation results show that the antenna's cross polarization level is better than-25 dB.A 2x2 dual circular polarization array using the unit was designed.A 4x4 dual circular polarization microstrip antenna array with a double layer structure was designed.We use a 3dB directional coupler polarization to be the converter.The measurement results show that the antenna has a high gain and good circular polarization performance;3 A four way power divider was designed and processed into physical test.We use such two power divider and 4 of the 4x4 antenna as a group,and four groups connected with the designed sum and difference network composed dual circular polarization microstrip 256 units antenna array.The array will be used for a monopulse antenna system.The measured results show that the average gain of the antenna system can reach 27 dbic,zero depth is less than-25 dB,and the working state of left-handed and right-handed circular polarization have high cross polarization ratio.Finally,the full text's work is summarized and some problems that need further research and improvement are proposed.