Design And Research Of Orbital Angular Momentum Communication Antenna

Nowadays,the world enters the information age.In order to get the latest and the most comprehensive multimedia information,there is an increasing demand on the transmission rate and transmission capacity of the signal.Orbital angular momentum(OAM)which was discovered in the 90 s of last century,has been applied to optics and photons,and it has been introduced to the microwave engineering in the first ten years of twenty-first Century.Orbital angular momentum is a new solution to improve the capacity of the channel with the characteristics of different modes that can be orthogonal to each other.Based on theoretical analysis and simulation processing test,three kinds of feed network based on substrate integrated waveguide(SIW)technology(30GHz)are designed to generate different modes of orbital angular momentum electromagnetic wave.The main contents of this paper include:Firstly,this paper introduces the background and significance of orbital angular momentum applied in the field of electromagnetic,and analyzes the generation characteristics of orbital angular momentum and the way to generate orbital angular momentum of circular antenna array in theory.After that,the characteristics of the Butler matrix feed network are reviewed,and some of the traditional network structures are analyzed and summarized in detail.Secondly,combined with the substrate integrated waveguide technology,this paper designs a variety of devices,such as-3dB directional coupler,cross coupler,and uses these devices designed to constitute a 2 × 4 feeding network.The Butler-fed array which has 4 waveguide slot antenna element employs a two-layer structure for size reduction.After simulation,processing and testing,it is proved that the scheme can generate two different modes of orbital angular momentum electromagnetic wave.Thirdly,in this paper,three kinds of shifter with different phase shift are introduced.By associating a 4 element circular antenna array to a 4 × 4 Butler feeding network,one can generate simultaneously and independently waves carraying 3 different OAM.After the simulation,the results verified the effectiveness of the proposed design for generating multi-mode OAM modes.Finally,a two-dimensional circular antenna array fed by two-layer 4×8 SIW Butler matrix is designed at 30 GHz.By using the two-layer structure to interate an 8 elements circulara antenna array and this matrix,4 different OAM modes of l =-3,-1,+1,and +3 can be generated.The feeding network uses a two-layer structure and two traditional 4×4 Butler matrix to reduce the use of crossover and the complexity of the whole network.Moreover,the whole scheme is fabricated and tested.According to the simulation and measurement results,it is proved that the effectiveness of the feeding network and the circular antenna array for generating OAM waves.