Research On Frequency Reconfigurable Microstrip Antenna

With the continuous development of modern radar and communication systems,more and more antennas with different functions are used in the system,which makes the antenna design more complex and the system integration higher and higher.Reconfigurable antenna can be loaded with adjustable devices to make one antenna have the function of multiple antennas,which provides a highly integrated and miniaturized solution for antenna system.Therefore,reconfigurable antennas covering a wide frequency range have a good application prospect in communication systems.At the same time,circularly polarized antenna has polarization insensitivity of electromagnetic wave,which can avoid polarization loss caused by polarization mismatch,and is widely used in satellite communication and other fields.In this paper,the wide-range reconfigurable linearly polarized and circularly polarized antennas are studied.The main innovations are as follows:(1)A wide frequency range reconfigurable linearly polarized microstrip antenna fed by slot coupling is designed.By introducing varactor diode between the main radiation patch and the parasitic element,the broadband frequency reconfiguration can be realized,and the parasitic element hardly affects the circuit path of the main radiation patch,so the antenna pattern characteristics will not be changed during the reconstruction process.The frequency reconfigurable microstrip antenna is continuously adjustable in the frequency range of 13 GHz to 19 GHz,the return loss in the operating frequency range is less than-10 d B,and the gain range is 3-6 d Bi.(2)In order to realize the circularly polarized microstrip antenna,a frequency reconfigurable circularly polarized microstrip antenna based on parasitic elements is designed.The frequency can be adjusted by loading varactor diode and controlling capacitance value to change the electrical length of antenna.In addition,the diagonal of the main radiation patch of the antenna is cut,and a varactor diode is loaded to make the two characteristic modes of the antenna orthogonal and equal in amplitude,thus realizing the stable circular polarization characteristics of the antenna in a wide frequency reconstruction range.Experimental results show that the designed antenna has a wide tuning range of 24%,a stable gain of over 7 d Bi and a radiation efficiency of over 85% in the range of1.9-2.3 GHz.The experimental results verify the good consistency between the experimental results and the simulation results.