RCS Reduction Of Antennas Based On Polarizaion Conversion Metasurfaces

As the rapid development of the modern military electronic technology, the sea, land, air, space, and electromagnetic five-dimensional will shape the future wars. Moreover, the low radar cross section(RCS) military platforms such as stealth warships and unmanned aerial vehicles(UAV) have drawn a lot of attention. Low RCS property of the carrier is the key factor which can reduce radar detection capability from enemy. Therefore, it can enhance the battlefield survivability and penetration ability of our carriers. For some small carriers, such as UAV, RCS contributed by antennas is a major contribution to the total RCS. As essential devices for a variety of radio equipment, the antennas are responsible for transmitting and receiving electromagnetic. Improving the stealth performance of the antenna and preserving the radiation characteristics simultaneously is the highlight for academia in the latest years. In the open literature, the RCS reduction techniques of antennas have been researched more than thirty years, which made some progress during the latest years. Nevertheless, radiation and scattering performance of antenna is a dilemma because antenna is a special scattering body. Moreover, the conventional RCS control technologies cannot simply be applied in antennas. This thesis studies RCS reduction of antennas by two kinds of polarization conversion metasurfaces(PCM). The thesis includes the following parts:1. Polarization Conversion Metasurfaces, as new artificial electromagnetic materials, the application of which has been applied to microwave band from terahertz and optical bands in the last 5 years. The reflection type and transmission type of polarization conversion metasurfaces have been described.2. RCS control technology by using polarization conversion metasurfaces have firstly been proposed in the open literature. The low-RCS surface has been used to design a low RCS slot array antenna. When illuminated by a normally impinging wave, the simulated and experimental results demonstrate that the monostatic RCS reduction band is from 6 GHz to 18 GHz. Meanwhile, the radiation performance of the antenna, such as boresight gain, impedance bandwidth, and radiation patterns has been well preserved. Furthermore, the mechanism of RCS reduction principles by using polarization conversion metasurfaces has been detailed analyzed.3. A novel chessboard polarization conversion metasurfaces(CPCM) have firstly been utilized to reduce the RCS of a circularly polarized antenna while increasing the antenna gain. This new type of CPCM is the chessboard configuration of the polarization conversion matasurfaces. On the one hand, such metasurfaces have the reflective characteristic which can rotate the polarization of the incident wave. On the other hand, such metasurfaces has the transmission feature which can transform a linear polarization wave to a circularly polarized wave. The simulated and experimental results show that wideband RCS reduction of the antenna by using the CPCM can be achieved as well as the widen circularly polarized axial ratio and the improved gain.