| The polarization conversion Metasurfaces is a device that is composed of metal unit structures with specific geometric shapes in a periodic arrangement,and the polarization direction of electromagnetic waves can be controlled by changing the structure of the Metasurfaces unit.Compared with traditional Metamaterials,it has the advantages of lower profile,lower loss,and easier integration of antennas.With the rapid development of modern radio technology,huge breakthroughs have been made in the fields of wireless communication systems,radar navigation,and carrier stealth.These increasingly complex systems and multi-tasking working modes have higher and higher requirements for antennas.Traditional antennas are no longer applicable.Polarization conversion Metasurfaces antennas are more capable because of their polarization diversity,high efficiency,and simple structure.It can better meet the needs of complex applications and has received extensive attention from researchers.This paper theoretically analyzes the working mechanism of Metasurfaces units,and designs different types of polarization conversion Metasurfaces to achieve arbitrary control of the amplitude and phase of electromagnetic waves.On this basis,applying it to the antenna can realize the linear-circular polarization conversion of the antenna,reduce the radar cross section(RCS)of the antenna and increase the gain of the antenna,which provides a new idea for the design of high-performance antennas.The main content and innovations of this article are as follows:The design of a high-gain circularly polarized antenna based on the polarization conversion Metasurfaces.First,the surface of the transmission-type polarization conversion Metasurfaces is analyzed,and a high-efficiency and wide-band polarization conversion Metasurfaces is designed by using the characteristics of the polarization conversion Metasurfaces to control the polarization of electromagnetic waves.Then,load it directly above the linearly polarized microstrip slot antenna,so that the original linearly polarized wave is converted into a circularly polarized wave,and the gain of the antenna is also improved.In order to study the influence of different parameters on the circular polarization characteristics of the entire antenna,each parameter was scanned and analyzed.Finally,the polarization conversion Metasurfaces antenna was fabricated,processed and tested.The simulation and test results show that it achieves good circular polarization characteristics in the 8.6-10.5GHz frequency band,and the measured gain is above 7d Bi in the 9.5-10.7GHz frequency band.A low RCS reflective screen based on the polarization conversion Metasurfaces is designed.First,a reflective polarization conversion Metasurfaces unit is designed,and the reflection coefficient of the reflective Metasurfaces unit is analyzed through software simulation.Then,the mirror image arrangement is used to make the polarization conversion Metasurfaces mirrored to each other have a phase difference of 180 degrees in the working frequency band,so that the scattered field is redirected,so as to achieve the effect of RCS reduction.The designed mirror-type polarization conversion Metasurfaces achieves an RCS reduction effect of more than 5d B in the 8.2-20 GHz frequency bandwidth than an ideal electrical conductor of the same size.A low RCS circular polarization high gain antenna is designed based on the mirror polarization conversion Metasurfaces.The mirror-type polarization conversion Metasurfaces is formed by arranging the polarization conversion array in a mirror-like manner,combining it with the microstrip slot antenna array,and designing a low-RCS circular polarization high-gain antenna.The simulation and measurement results show that the designed loaded mirror polarization conversion Metasurfaces antenna not only realizes the reduction of single station RCS in the frequency range of 8.2GHz to 20 GHz,but also broadens the axial ratio bandwidth of circular polarization and improves the antenna gain. |
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