Research On Low Scattering Antenna Based On Metasurface

The development of modern technology has greatly improved the application of electronic technology in the military.Electronic warfare and information warfare have become important way of modern military confrontation.Radar detection technology has greatly improved combat capabilities.Correspondingly,radar stealth technology can enhance the survivability of the weapons and increases the threat to the enemy.The key to radar stealth technology is to reduce the radar cross section(RCS)of the scatterer.Antenna is a special scatterer,so it is critical for enhancing the stealth capability of military equipment to reduce antenna's RCS in a wide frequency domain and wide-angle domain while maintaining its radiation performance.The electromagnetic metasurface provides a new method for reducing the scattering of the antenna.Its special electromagnetic characteristics can effectively reduce the RCS of the antenna and design a low-scattering antenna.This thesis mainly studies the application of electromagnetic metasurfaces in RCS reduction of antenna.The main research contents are as follows:1.Based on the electromagnetic wave polarization conversion theory,a polarization conversion unit with high polarization conversion rate in a wide frequency band is designed.Two polarization conversion units with different sizes are selected to construct a 6x6 double-layer polarization conversion metasurface,which can achieve an RCS reduction of 10 d B within a band of 22.8 GHz-45.8 GHz.The double-layer polarization conversion metasurface reduces the area of the metasurface and expands the RCS reduction bandwidth.It can be verified through simulation and processing test that the double-layer metasurface is loaded on the microstrip antenna,and the in-band and out-of-band RCS of the antenna can be reduced without affecting the radiation performance of the microstrip antenna.2.Rotating the metal patch of the polarization conversion unit to obtain 8 different units.Utilizing their stable scattering coefficient phase difference with circularly polarized incident wave,two phase gradient metasurfaces are designed to deflect the main beam of the scattered wave,which let the main beam far away from the most threatened angle,to reduce the radar cross section.Two phase gradient metasurfaces can achieve more than 10 d B RCS reduction in the 21.2GHz-44.6GHz frequency band.3.Encoding 8 rotating units,and designing an encoding metasurface through the numerical calculation method of two-dimensional scanning array and genetic algorithm.The coding metasurface has low scattering characteristics in a wide frequency domain and a wide angle domain,and can achieve an RCS reduction of more than 10 d B in the frequency band of 21.2GHz-46.5GHz.Using the coding metasurface to replace the metal reflector of the microstrip Yagi antenna can achieve broadband RCS reduction while keeping the radiation performance of the Yagi antenna unchanged.