Design And Study Of Millimeter Wave Antenna Based On Orbital Angular Momentum

With the development of mobile Internet applications,spectrum resources are becoming increasingly scarce.Traditional techniques to improve spectrum utilization,such as orthogonal frequency division multiplexing,time division multiplexing,code division multiplexing,etc.,can no longer meet the high speed and complex signal transmission.5G white paper mentions a key technology to improve spectrum utilization-Orbital Angular Momentum(OAM).OAM has attracted a lot of attention in many fields due to its potential to unlock new capacity in the heavily congested spectrum of communication systems.Especially in the field of telecommunications.The beam carrying OAM has a helical phase wavefront and a field strength with singularity along the axial center.Each carrier is capable of carrying an OAM beam with an infinite number of modes,each mode being a complete orthogonal base unit.Therefore,different modes do not interfere with each other and can be used for multiplexing of different signals,thus greatly improving spectrum utilization.At the same time,the millimeter-wave band has abundant spectrum bandwidth resources,which is especially critical to meet the high traffic demand while ensuring the performance and quality of communication.In this paper,OAM is combined with millimeter wave,and the main focus is on the generation method of multimodal OAM beams in millimeter wave band.(1)In this paper,a dielectric resonator with low loss and high dielectric constant is used as the main body of the antenna.The transmission characteristics and field distribution of the cylindrical dielectric resonator antenna are studied theoretically.The feasibility of generating OAM from a cylindrical dielectric resonator is theoretically verified with the help of the ring phased array principle.In this paper,a multi-frequency multi-modal OAM antenna is designed,which is capable of generating four different modal OAM beams at four different frequency points in the millimeter wave band.The signal can be transmitted using both modal and frequency degrees of freedom,and its application to a joint vortex EM wave-based hopping mode-frequency anti-interference system can achieve better anti-interference effects.(2)In order to further explore the multiplexing performance of OAM antenna,an array antenna based on rectangular dielectric resonator is designed.This antenna consists of 12 rectangular dielectric resonators with high-band,ultra-wideband,and multi-mode characteristics.The radiation characteristics of the rectangular dielectric resonators are analyzed,and the coupling effects between the array antennas are analyzed.In addition,the OAM-MIMO communication capacity is verified,and it is shown that the application of the antenna to the OAM-MIMO system can effectively improve the channel capacity of the communication system,which provides some practical significance for the modal multiplexing of OAM in the millimeter wave band.(3)In this paper,the radiation mechanism of Circular Polarization(CP)antenna is analyzed,and the circular polarization antenna is applied to a circular phased array to avoid the use of multi-port phase shifter and the design of complex feed network,which greatly simplifies the complexity of OAM multiplexing system.In this paper,a double-ring concentric uniform circular array(4 inner rings and 8 outer rings)composed of 12 circularly polarized antennas is proposed.By rotating the circularly polarized antennas by a certain angle so that each array element has a different phase,the antennas are rotationally symmetric and point to the center,so that the generation and switching of two OAM modes can be achieved by feeding the same amplitude and phase.