| In the last decade,the wide application of wireless communication services has generated an over-whelming demand of wireless communication system for high-speed,large bandwidth,and efficient wireless channels.It's essential for wireless applications to increase the channel capacity and raise the rate of data transmission in future,Unfortunately,the available band is too crowded.It has been proved that it is very difficult to further expand the bandwidth for wireless communication system to overcome this problem.Recently,a technology called OAM multiplexing has opened up a new direction for wireless communication system.It can create an infinite number of mutually orthogonal modes to transmit electromagnetic wave as the carrier.Because of this unique multi-mode transmission,it can transmit different data with the same channel at the same frequency as a carrier.OAM multiplexing technology has shown a broad application prospect in improving spectrum efficiency.In this paper,firstly,it proposes a solution to the current situation of spectrum resource shortage by using OAM vortex electromagnetic wave multiplexing technology.Secondly,according to the basic theory of OAM,it describes a lot from the generation of OAM to the reception and detection.Next,it accounts with the center of the design principles of OAM vortex electromagnetic wave array antenna,which includes the basic principles of rectangular microstrip patch antenna,circular polarization theory of rectangular microstrip patch antenna and the design principles of OAM vortex electromagnetic wave array antenna.Finally,in order to provide more reference for the future application of OAM vortex electromagnetic wave,it raises several excellent designs of OAM vortex electromagnetic wave microstrip array antenna with the help of a simulation software which is called ANSYS HFSS.The main research work of this paper can be roughly divided into the following three points:(1)Aiming at the problem of narrow bandwidth of microstrip patch antenna,in order to cover a large bandwidth,a design of K/Ka band dual-frequency OAM array antenna is proposed,and the antenna can generate OAM vortex electromagnetic wave with good wave-front structure in two bands.(2)This paper designs a right circular polarization receiving OAM array antenna that can work in the band L1 of GPS based on the circular polarization theory of rectangular microstrip patch antenna by using a unique feeding method.It's return loss,voltage standing wave ratio,axial ratio and other characteristics are good,and the 3D directional diagram and electric field vortex diagram show that the antenna has good radiation characteristics.(3)In view of the traditional complex design of feeding network and the problem of huge volume,this paper puts forward a new type of feeding network for an 8 element single-mode OAM microstrip array antenna with the center frequency of 24 GHz,the phase error of feeding network within ±1 °,the array antenna has good characteristics of vortex.(4)In order to solve the problem that an array antenna fed by fixed network generates single mode l,this paper proposes an 8 element multi-mode OAM microstrip array antenna fed by coaxial cable with a center frequency of 24 GHz.The array antenna not only achieves perfect match of impedance but also good radiation performance and obvious vortex characteristics. |
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