Design Of Broadband Circularly Polarized Antenna

With the rapid development of mobile communication technology,the demand for bandwidth of communication systems continues to grow.Therefore,how to expand antenna bandwidth has always been a hot spot in the industry and academia.Circularly polarized antennas have the advantages of Suppressing multipath transmission interference and reducing polarization mismatch loss.It is widely used in satellite navigation,radio frequency identification technology(Radio Frequency Identification,RFID)and other fields.Therefore,the design of a circularly polarized antenna with broadband characteristics can not only meet the large bandwidth requirements of the communication system,but also can give full play to the technical advantages of the circularly polarized antenna.Broadband circularly polarized antennas have good application prospects and research value.This thesis focuses on the broadband circularly polarized antennas.The main contents include:1.Design of a broadband low-profile backfire circularly polarized antenna.Firstly,a design scheme of backfire pattern based on traditional monopole is proposed.The scheme includes two parts:?shaped antenna design and?shaped antenna placement design.Compared with the traditional backfire design,this backfire design has lower requirements on the ground size,so it reserves sufficient space for the design of the subsequent broadband feeder network;Then a backfire circularly polarized antenna is designed based on the backfire scheme,and a broadband phase-shifted feeder network matched with it is designed.In the end,the antenna obtains a larger impedance bandwidth(0.83-2.53 GHz),an axial ratio bandwidth(1.15-2.25 GHz)and a lower antenna profile height(0.14?₀).Compared with the traditional backfire antenna,the antenna of this design has a larger bandwidth and a lower profile height.2.Design of a broadband high-gain circularly polarized antenna suitable for the5th Generation mobile communication technology(5G).The?shaped antenna has good directional radiation characteristics when it is placed away from the edge of the dielectric plate.Therefore,based on the good directional radiation characteristics of the?shaped antenna,a broadband high-gain circularly polarized antenna suitable for 5G systems is designed.In the end,the antennas each cover a Sub 6G frequency band(1.61-4.11 GHz)and high gain(13.3 d Bi).3.Design of a wideband widbeam low-profile circularly polarized antenna is designed.The antenna design includes two parts:the main radiating patch design and the coupling patch design.The main radiating patch is a square patch,and the coupling patch is a bent grounded patch.The bent coupling patch expands the bandwidth of the antenna and reduces the overall size of the antenna.At the same time,the vertical structure is introduced by the benting coupling patch which widens the half-power beam width of the antenna.In the end,the antenna obtained a large impedance bandwidth(1.03-2.14 GHz)and an axial ratio bandwidth of(0.79-1.86 GHz).At the same time,a larger beam width and a lower profile(0.06?₀)are also obtained.The antenna is a circularly polarized antenna with broadband,wide beam,and low profile characteristics.