Research And Design Of Vortex Electromagnetic Wave Antenna Based On Orbital Angular Momentum

With the development and application of 5G technology,the field of wireless communication applications continues to expand,and the number of mobile terminals has also exploded,which places higher requirements on the transmission rate and transmission capacity of the communication system.The vortex electromagnetic wave carrying the orbital angular momentum has a helical phase factor ejl?,which indicates that the vortex beams with different modes are orthogonal to each other.It brings new degrees of freedom to signal multiplexing technology.Therefore,researching and designing vortex electromagnetic wave antennas that carry orbital angular momentum has become a focus of research on vortex electromagnetic waves.Based on this,this paper proposes two forms of vortex electromagnetic wave antennas:circular array and single patch,and analyzes the impact of related structures on antenna performance.The main contents are as follows:Firstly,the research progress of vortex electromagnetic wave antennas at home and abroad is summarized,the theory of orbital angular momentum and vortex electromagnetic waves are explained,three ways of generating vortex electromagnetic waves:spiral phase plate,circular array,and resonant cavity antenna are analyzed,which lay a theoretical foundation for the design of the following antenna.Secondly,a deformed butterfly-shaped dipole antenna is designed,and the influence of structural parameters such as the length of the dipole arm,the width of the dipole arm,and the length of the balun feed transmission line on the antenna performance is analyzed,and the optimized world parameters are given.The-10dB impedance bandwidth of the antenna is 9.41?11.82GHz,the maximum gain is 6.46dB.Using the designed antenna as array elements,the effects of array element distribution mode,number of elements,and array radius on the radiation performance of antenna working bandwidth,gain,wavefront phase distribution,etc.are analyzed.Finally,based on the cavity mode theory,three types of vortex electromagnetic wave antennas with simple feed structures are designed:a planar double-fed circular patch antenna,a planar single-fed circular patch antenna,and a planar single-fed elliptical patch antenna.By adjusting related parameters,the antenna works in TMnm,radiating vortex electromagneticwaves in OAM mode l=|n-1|.The influence of structural parameters such as the radius of the feeding point and the azimuth angle of the feeding point on the radiation performance of the antenna S11 parameters,the radiation OAM mode,and the wavefront phase distribution are analyzed.Taking a uniform circular array composed of a flat single-fed circular OAM antenna carrying mode l=1 and l=-1 as an example,the relationship in the case of the same feed phase difference between the OAM mode larray generated by the uniform circular array when the array element carries the OAM mode lelement and the OAM mode lun generated by the uniform circular array when the array element does not carry OAM is explored,as larray=lun+lelment,wherelarray,is still restricted by the number of elements N for-N/2+lelement<larray<N/2+lelement.