Research And Design Of Circular Polarization Reconfigurable Navigation Antenna Based On Single Element

Global Navigation Satellite System(GNSS)can provide real-time,high-precision location and time information services via satellites.It not only plays an important role in the field of defense and military applications,but also has wide attention,study applications in scientific research and the national economy.As an indispensable part of the GNSS,the antenna's performance somehow determines whether the whole system can play its role and function.The antenna is subjected to multipath interference during signal reception,the main solution is to reconfigure the pattern through antenna arrays.However,array antennas have obvious difficulties and shortcomings.For example,the coupling between elements,large volume,complex design debugging process,the back-end need to match the corresponding algorithm and receiving chip,and the high cost.At present,commercial GNSS antennas are mostly simple single-patch microstrip antennas because of their simple design and processing and low cost.Based on the current situation and the difficulty of array antenna,this subject aims to design a single-patch microstrip antenna with simple structure to realize the reconfigurable function of axial ratio or pattern.In this paper,the microstrip antenna model is first established.Based on the model,the derivation of the relationship between the amplitude and the phase of the feed polarization in any direction is given.The relationship between the circular polarization direction and the feed amplitude and phase is obtained formula.In order to verify the theoretical derivation,a dual feed circularly polarized microstrip antenna is designed with working frequency of 1.575 GHz in the L1 band of GPS.Then change the feed amplitude under the condition of a fixed feed phase difference of 90 degrees.The simulation results show that the theoretical calculation is correct.In order to further verify this conclusion,the model was processed and measured.The measured results of axial ratio in two special planes are in good agreement with the simulation results.Due to the instability of the phase center of the dual-fed microstrip antenna model,a four-feed microstrip patch antenna is designed and simulated to solve this problem.The reconfiguration theory of gain was studied and verified by changing the phase of the feed,and the theory of axial ratio reconfiguration was discussed.