| With the large-scale development and utilization of microwave frequency band,With more frequency bands to be developed,millimeter wave band has gradually become the focus of researchers and engineers.The broadband spectrum of millimeter wave band and the miniaturization of devices make it possible to have high capacity and high data transmission in the future.Antenna is an essential front-end device in millimeter wave communication system,so many kinds of planar millimeter wave antennas have been widely studied.Circularly polarized antenna has the merits of resisting polarization mismatch,suppressing multipath fading and reducing rain and fog interference.It is widely used in satellite communication,radio frequency identification,radar electronic countermeasures and so on to improve link quality.This paper focuses on millimeter wave circularly polarized antennas in different application scenarios,research and design of two types of planar circularly polarized array antennas focusing on Ka band.The specific work content is as follows:1.A Ka band low profile wideband circularly polarized array antenna is proposed.Firstly,a wideband circular polarization element loaded with hexagonal parasitic patches is proposed.Based on the single axial ratio resonance point of the traditional circular polarization magnetoelectric dipole,a second axial ratio resonance point is introduced to achieve 27.1% impedance bandwidth and 16.3% axial ratio bandwidth.Then,a 2×2 subarray is constructed by using a sequential rotating feeding network composed of Substrate Integrated Waveguide(SIW).Finally,a 4×4 array antenna is designed based on the subarray and verified by experiments.The test results show that the antenna array achieves 27.7% impedance bandwidth and 28.5% axial ratio bandwidth,and the antenna within the bandwidth has good radiation characteristics of right hand circularly polarized(RHCP),which is suitable for Ka band wideband circular polarization communication system.2.A Ka band 5G millimeter wave dual-band dual-circularly polarized array is proposed.Firstly,two kinds of circularly polarized radiation are generated in two bands by means of degenerative mode separation of SIW resonator and rectangular patch.Then the stacked parasitic patches and shorted via holes in the patches were introduced to adjust the resonance points to the desired bands.Finally,a 4×4 array antenna is designed by using the designed element structure and a compact microstrip full corporate feeding structure,and the experimental verification is carried out.The test results showed that the proposed array antenna radiated RHCP at 28 GHz and left hand circularly polarized(LHCP)at 38 GHz.The two bands achieve impedance bandwidth of 7.3% and 7.5%,and axial ratio bandwidth of 2.8% and 2.6%,respectively,which are suitable for 5G millimeter wave circular polarization full duplex communication system. |
