Research On Feed Of Radial Line Slot Antenna For Beam Scanning

Limited by physics and technologies,the output capacity of a single high-power microwave(HPM)source can hardly be further improved.Therefore,researchers have paid more attention to improve the equivalent radiation power by using space power synthesis technology.The single HPM source radiation system for space power synthesis is a key technology that must be overcome,among which beam scanning antenna is the key component.Under this background,radial line slot antenna(RLSA),which can be matched with the rotating lens,is researched and used as the feed of rotating lens beam scanning antenna system.This research lays the foundation for the study and design of high performance and compact HPM beam scanning antenna.The detailed content of the dissertation includes the following parts:1.Research on beam-tilted circularly polarized RLSA.2-D beam scanning can be realized by matching a beam-tilted circularly polarized RLSA with a single-layer phase shifting lens.Therefore,research on beam-tilted circularly polarized RLSA is carried one firstly.According to the basic theory of RLSA,a simplified rectangular waveguide model is used to design the all-metal radial slow wave structure.The basic principle and design method of the circularly polarized radiation element are analyzed,and the slot arrangement of the beam-tilted helical array is deduced.TEM mode is fed into the coaxial waveguide and radiated in circularly polarized form.A fixed angle deflection of the main beam from the normal direction is also realized.Numerical simulation results show that the antenna of 600 mm diameter,working at 14.25 GHz,with a tilting angle of 10 degree,has a gain of 35.6 dB and an efficiency of 45.28%.The tilting angle of the main lobe is 10 degrees,and the axial ratio is 0.98 dB.Then,the antenna is jointly simulated with the single-layer phase shifting lens.The numerical simulation results show that a tilting angle of less than 20 degrees in elevation can be realized.The gain of the antenna system is above 35.1 dB,and the efficiency is 41.3%.The main lobe axial ratio is less than 0.867 dB.The power handing capacity of this antenna system reaches GW level.2.Research on axial radiating circularly polarized concentric array RLSA.Research on concentric array RLSA is carried out in order to improve the aperture efficiency of RLSA feed.According to the basic theory of concentric array RLSA,the numerical method is used to show this array has the advantages of high gain,low sidelobe,good far-field radiation patterns and high aperture efficiency.It has a good prospect in the HPM field.According to the principle of equivalent circuit,the impedance distribution of the slot elements on the aperture surface is calculated,and the relationship between the normalized equivalent resistance of the slot and the radial position of the slot is obtained.Models are built to extract the equivalent electrical parameters,and the relationship between the normalized equivalent resistance and the structure parameters of the radiating element is derived.The numerical simulation results show that the circular polarized concentric array RLSA of 600 mm diameter,working at 14.25 GHz,has a gain of 37.07 dB an efficiency of 70% with a 0.055 dB axial ratio.Then,the antenna is jointly simulated with the single-layer and the double-layer phase shifting lens.The numerical simulation results show that a tilting angle of less than 20 degrees in elevation can be realized.The gain of the antenna system is above 36.6 dB,and the efficiency is 57%.The main lobe axial ratio is less than 0.16 dB.The power handing capacity of this antenna system reaches GW level.3.Research on linearly polarized concentric array RLSA.A kind of concentric array RLSA based on linearly polarized radiation element is presented and studied,in order to research the design of RLSA based on standing wave array.A kind of linear polarized radiation element is designed.The radiation elements are arranged concentrically,so that the electric field line above the aperture surface is impedance distribution of the slot elements on the aperture surface is calculated strictly.Models are built to extract the equivalent electrical parameters,and the structural parameters of linear polarized radiation elements on each round are obtained.On the basis,a linearly polarized concentric array RLSA is designed,with a diameter of 600 mm and working at 14.25 GHz.The numerical simulation results show that this antenna can radiate TEM mode,and the pattern is ring-like.The main lobe is located at 1.8 degrees,and the maximum gain is 31.61 dB.The sidelobe is-16.8 dB.Then,the antenna is jointly simulated with the double-layer phase shifting lens to achieve a solid beam.The numerical simulation results show that the pattern of this antenna system has an axial peak.The maximum gain is 36.8 dB,and the efficiency is 59.7%.The main lobe axial ratio is 2.61 dB.Finally,the antenna is jointly simulated with three layers of phase shifting lens to realize 2-D beam scanning.The numerical simulation results show that the 2-D beam scanning can be realized.With a tilting angle of 14.25 degrees in elevation,the gain and efficiency of the antenna system is 35.15 dB and 40.8%,separately.The main lobe axial ratio is 0.32 dB.