Research On Vortex Electromagnetic Wave Generation Technology With Multi-topological Charges

In recent years,in order to improve channel capacity and spectrum utilization,and to make communication networks more reliable and safe,Orbital Angular Momentum(OAM)technology has been used.At present,the method of generating vortex electromagnetic waves using array antennas has been extensively studied,but due to the high cost of phase shifting devices in the array,it is not conducive to mass production and manufacturing.Therefore,in order to reduce the cost of the phased array that generates vortex electromagnetic waves,the relevant theories of vortex electromagnetic waves are still worthy of in-depth study.First of all,this thesis is mainly based on the basic theory of antenna arrays,and analyzes and studies the typical characteristics of several uniform array antennas in detail,including uniform linear arrays,uniform planar arrays and uniform circular arrays.Then the basic theory of vortex electromagnetic waves carrying orbital angular momentum is studied.Based on this theory,several main methods of generating vortex electromagnetic waves are studied.Secondly,the method of exciting the vortex electromagnetic wave by the uniform circular array is studied in detail,and based on this method,a new method of exciting the vortex electromagnetic wave based on the fixed delay line is proposed.The core is to use a fixed delay line to replace the phase shifter in the traditional phased array,and to derive the basic formula for the signal frequency to delay the phase of the delay line.In addition,a uniform circular array system based on fixed delay lines with 8 elements and 16 elements is simulated to verify whether the method can successfully generate vortex electromagnetic waves.Then,according to the simulation results,the influence of different parameters on the generation of vortex electromagnetic wave and its topological charge is analyzed.The method uses a delay line to replace the phase shifter,which greatly reduces the cost of the method for generating vortex electromagnetic waves,and thus plays a great role in the wide application of vortex electromagnetic waves.Subsequently,the principle of phased array scanning is studied,and the specific methods of one-dimensional scanning array and two-dimensional scanning array to control beam steering are analyzed.According to this principle,the formula that the vortex electromagnetic wave should meet at the specified angle is derived,and it is combined with the proposed method of vortex electromagnetic wave excitation based on the delay line.Furthermore,a design method of vortex antenna with arbitrary orientation based on phased array is proposed,and a uniform circular array of 8elements is used to verify the design method.Finally,according to the proposed method for generating excited vortex electromagnetic waves based on a fixed delay line,a physical system is built for verification,and an antenna array with 8 elements is tested,which can generate vortex electromagnetic waves with a maximum topological charge of 3.