Design And Research Of Phase Gradient Metasurface Applied To Beam Control

With the development of wireless communication since 21 st century,antenna,as the receiver and launcher of wireless communication system,is an important part of the wireless communication system and its performance will directly affect the quality of wireless communication products.Nowadays,the traditional design method will not meet all the indicators for the development of antenna turning towards miniaturization,intellectualization,high gain,broadband,wide beam and so on.Electromagnetic metamaterials are artificial electromagnetic material with unique physical properties,which are not found in nature,and loading them onto antennas can improve the performance of antennaCompared with the three-dimensional Electromagnetic metamaterials,the two-dimensional electromagnetic metasurface has the advantage of small size,low loss and low cast,so it gets wide attention and research.Phase gradient metasurface,as a kind of electromagnetic metasurface,can realize the wave-front manipulation of electromagnetic wave by introducing different phase mutations at the interface.At present,according to the generalized Snell's law,a variety of functions have been realized by using phase gradient mteasurface,such as lens,beam control,anomalous reflection or refractionand surface wave coupling.The goal of this paper is to realize the deflection of transmitted beam by using phase gradient metasurface,and the main research content includes the four parts below:Firstly,this paper introduces the related theory of phase gradient metasurface and Fabry-Perotcavity antenna.For the phase gradient metasurface,this paper introduces the generalized Snell's law,which includes the generalized Snell's reflection and refraction laws.The array boundary conditions of the phase gradient metasurface is also studied.For the Fabry-Perot cavity antenna,this paper introduced the working principle of the Fabry-Perot cavity antenna.Secondly,a transmission phase gradient metasurface in the form of multi-layer square patch is designed.and it can realize the beam deflection in C band.In the first,this paper analyzes the transmission characteristic of the multi-layer square patch unit.As the transmission coefficient of the last unit is too low,four rectangle slots is opened from the original structure to increase its transmission coefficient.The slots are with an angle 45 degrees at each of the four corners of the square patch.On this basis,the designed phase gradient metasurface is loaded onto the horn antenna.The deflection effect of the phase gradient metasurface is simulated and analyzed.In the last,the designed phase gradient metasurface is processed and measured,and the results show that it can realize the transmission beam deflection of about 25 to 30 degrees in the frequency range of 5.3GHZ to 6.3GHz.Thirdly,by using the idea of phase gradient metasurface,this paper designs an electromagnetic metasurface structure with a certain phase gradient.And the designed structure is used as the partially reflective surface of the Fabry-Perot cavity antenna.The feed antenna of the Fabry-Perot cavity antenna uses the traditional microstrip patch antenna.The simulation finds that the designed Fabry-Perot cavity antenna can realize the beam deflection between 41 degrees to 43 degrees in the frequency range of 5.7GHZ to 5.9GHz.And the gain can reach 9d Bi to 10 d Bi in the maximum radiation direction.Lastly,the idea of phase gradient metasurface is introduced into the design of the Mushroom antenna.Two Mushroom antennas are designed.One is the traditional Mushroom antenna structure with the same unit structure,and the other is the Mushroom antenna with the gradient element structure by introducing the idea of phase gradient metasurface.The simulating results show the impedance bandwidth of the Mushroom antenna with the gradient element structure is 4.7GHz~5.3GHz and the relative bandwidth is 12%,which is reduced compared to the traditional Mushroom antenna,however,it can realize the beam deflection of 20 degrees to 30 degrees and the maximum radiation direction gain is 6.5d Bi to 7.5d Bi in the working band.