Research On In-band Low RCS Leaky Wave Antenna Array Integrated With Metasurface

The metasurface has unique electromagnetic properties and flexible manipulation of electromagnetic waves can be achieved by designing the structure and arrangement of metasurface units.Adopting the integrated concept of radiation and scattering,a leaky-wave antenna is designed based on the Substrate Integrated Waveguide(SIW)in this dissertation.Without affecting the radiation performance of the antenna,the low-scattering coding metasurface is loaded on the leaky wave antenna,realizing the polarization-independent reduction of the Radar Cross Section(RCS)in the frequency band of antenna.In this dissertation,the main contents are summarized as follows:(1)Serial and parallel feeding SIW periodic leaky wave antenna arrays in the Ka-band are designed.The antennas utilize the periodic structure for introducing high-order spatial harmonics to leaky radiation.Meanwhile,a back-fed SIW feed network and SMA-SIW transition structure are designed to make the overall antenna compatible with printed circuit board technology.Increasing the number of slots in the direction perpendicular to the traveling wave,the gain of the designed parallel-fed SIW periodic leaky wave antenna array is improved and the beam scanning range over 25° is achieved.The gradient phase of antennas in two directions,which are parallel and perpendicular to the traveling wave is constructed in the series-fed SIW leaky wave antenna array.The antenna scanning beams can cover two-dimensional space,including the range of-4°~10° in the xoz plane and-30°~40° in the yoz plane.The both designed leaky wave antennas have the advantages of low profile,low cost,easy processing,high integration and stable performance.(2)A reflective 1bit coding metasurface with integrated radiation and scattering is designed based on the inherent structure of the aforementioned SIW leaky-wave antenna array.In 28.8 GHz~29.8 GHz,isotropic ‘0' and ‘1' metasurface elements are designed,which can maintain 180° phase difference for both x-polarized and y-polarized incident waves and the phase difference can be kept within 20° of oblique incidence.Subsequently,the influence of different coding arrangements on the RCS reduction of the integrated metasurface is studied.The simulation results show that the RCS reduction effect of the random coding metasurface is better than that of the checkerboard.(3)Two low RCS metasurface-SIW leaky wave antenna arrays are designed.Combining the design of random coding stealth metasurface and SIW leaky wave antenna array,integrated design is applied based on the concept of integrated radiation and scattering.Without affecting the radiation performance of the antenna,the designed backward and broadside metasurface-SIW leaky wave antenna arrays can achieve polarization-independent RCS reduction over 5 d B.The measurement results show that the designed low RCS metasurface-SIW leaky wave antenna arrays possess a good stealth performance in different radiation directions,hardly affecting the radiation performance of the antenna.