| Due to the metasurface has the characteristics of low profile and special response to electromagnetic wave,it has a wide application prospect in mobile communication,satellite navigation and other fields.The integration of some controllable devices（PIN diodes,varactor diodes,etc.）into the active metasurface can realize the flexible control of electromagnetic waves and further expand the application field of the metasurface.In this paper,based on the active metasurface,the phase of the electromagnetic wave radiated by the feeding antenna is controlled to realize the control of the far-field radiation beam of the antenna and the reconstruction of the working frequency of the antenna.The main works of this paper are as follow:1.Research and design of single-layer active transmission metasurface.According to the reversal effect of current,a symmetrical composite J-shaped metasurface unit is proposed,and the phase control of the metasurface unit is realized by loading PIN diodes.Combining the phase compensation theorem and the far-field radiation formula,the metasurface unit is arrayed and encoded to achieve the performance of beam control.Two feeding antennas are designed and loaded to 0.11λ0 below the metasurface.The simulated and measured results show that the dual-beam deflection of the antenna is realized.After only changing the feeding antenna,multi-beam and beam scanning of±60°in E-plane are realized,and the peak gain is 11.1 dBi.2.Research and design of multi-layer active transmission metasurface.Aiming at the limitations of narrow working bandwidth and large influence of bias line of single-layer metasurface,a multi-layer transmission metasurface unit working in Ka-band is proposed based on the generalized Snell’s law.Each unit integrates two PIN diodes to achieve 1-bit quantization of phase.Based on the principle of phase compensation,the metasurface unit is coded to achieve the performance of beam steering.Two feeding antennas are designed and loaded below the metasurface.The research shows that the multi-beam switching and dual-beam deflection of the antenna are realized.After only changing the feeding antenna,±40°beam scanning is realized,and the peak gain is 12.5 dBi.Compared with the single-layer metasurface antenna,the operating bandwidth of the multi-layer metasurface antenna is increased by 4.7%,and the sidelobe level is reduced by 4d B.3.Research and design of dual-polarized reflective frequency selective surface.Based on the filtering characteristics of the frequency selective surface,a dual-polarized frequency selective surface unit is proposed,which combines varactor diodes to achieve 360°continuous phase tunable performance.Based on the proposed frequency selective surface unit,a 5×5 periodic array is designed,and the planar dipole antenna is used as the feeding antenna.The simulated and measured results show that the antenna achieves a continuous frequency adjustment of 2.5GHz-5.4GHz based on the active frequency selective surface,and the relative bandwidth is 73.4%.Compared with the single feeding antenna,the relative bandwidth is increased by 55.2%and the peak gain is increased by 7.1dBi. |
