基于极化旋转超表面的圆极化天线设计

A circular polarization antenna designed based on the polarization conversion metasurface

本文通过设计出一种反射型极化旋转超表面,在8—12 GHz频域内实现高效的极化旋转,并将其加载于微带缝隙天线下方构成新型的极化旋转超表面天线,利用超表面的90°极化旋转效应,成功实现了天线的圆极化辐射调制.仿真与实验结果表明:圆极化天线的中心工作频率为GHz,阻抗带宽为8.3—10 GHz.当微带缝隙天线与极化旋转超表面的间距H=4.5mm时,天线在8.3—8.8 GHz频带内实现了圆极化辐射;当mm时,天线在8.8—9.3 GHz频带内实现了圆极化辐射;当=8mm时,天线在9.3—10 GHz频带内实现了圆极化辐射.实验结果与仿真结果相符,证明了此种设计方法的有效性,也为微带缝隙天线的圆极化设计提供了一种新的途径.

A novel circular porlarization （CP） antenna is designed and fabricated by loading a kind of polarization conversion metasurface. The structure of polarization conversion metasurface is composed of metal slash and copper ground sheet, which is separated by an FR4 dielectric substrates with a thickness h = 3 mm. When a normal electromagnetic wave incident on the whole surface vertically, the electric field of the wave can be decomposed into two components Evi and Evi. Under the excitation of the two components, resonance is induced between the metal slash and the copper ground sheet respectively, making their own reflection phase changed to △=φu -φv = ±180°, eventually making the reflection wave appear with 90° polarization rotation. By taking the peculiarity of 90°polarization rotation of the polarization conversion metasurface, we can modulate the linear polarization of microstrip slot antenna into the circular polarization radiation. Through adjusting the distance between the slot antenna and the polarization rotation metasurface, we can regulate the working frequency of the circular polarization. Simulated and experimental results show that the polarization conversion metasurface makes a high-efficiency polarization rotation at 8-12 GHz. And the center working frequency of the CP antenna is 9.1 GHz, the impedance bandwidth is 8.3-10 GHz. When the distance H = 4.5 mm between the microstrip slot antenna and the polarization conversion metasurface, the 3 dB axial ratio bandwidth is 8.3-8.8 GHz, the microstrip slot antenna may realize circular polarized radiation. When H =20 ram, the 3 dB axial ratio bandwidth is 8.8-9.3 GHz, and the slot antenna can realize circular polarized radiation. When H = 8 mm, the 3 dB axial ratio bandwidth is 9.3-10 GHz, the slot antenna can realize circular polarized radiation. Experimental results are in agreement with the simulation results, showing the validity of this design method which may become a new approach for the CP antennain designing