Research On Reconfigurable Beam Scanning Antennas

With the rapid development of modern wireless communication technology,higher requirements for antenna performance have been put forward in the communication system.The performance of traditional antennas is fixed and single,which cannot meet the diverse application requirements.Therefore,the reconfigurable characteristics of antennas have been paid more and more attention by researchers.Leaky wave antenna(LWA)is a common beam scanning antenna with a simple structure and mature research theory.The beam direction changes with frequency.However,most communication systems work in a specific frequency band,and the frequency scanning characteristics of LWAs are not applicable.The combination of reconfigurable technology and frequency scanning LWAs can realize the reconfigurable beam scanning function of the antenna at a fixed frequency,which can improve the application scenarios of LWAs and has high research value.In this paper,the design of reconfigurable beam scanning antenna is studied in depth.The main research contents are as follows:1.A reconfigurable microstrip LWA with half-long stubs is proposed.The structure of the traditional periodic microstrip LWA is improved,the stub length is reduced by half,and the quarter-wave impedance converter is loaded to eliminate the open stop-band phenomenon of the LWA.Finally,the varactors are loaded,and an electronically control method is adopted to enable the antenna to perform beam scanning at a fixed frequency.2.A reconfigurable circularly polarized LWA based on digital coding is proposed.First,a composite right/left-handed(CRLH)structure LWA is designed.Then shunt stubs are introduced on the antenna unit cell,and PIN diodes are loaded as switches to change the impedance loading of the stubs,thus the dispersion characteristics of the antenna can be controlled.Moreover,encoding the switch state to control the antenna beam angle.3.A reconfigurable LWA based on the HM-BCSIW structure is proposed.Firstly,the structure and transmission characteristics of HM-BCSIW are analyzed,and a CRLH LWA is designed using this structure.Then varactors are loaded to adjust the equivalent circuit and phase constant,leading to a change in the beam direction.The antenna can be continuously scanned from forward to backward at a fixed frequency.