Research On Wide Angle Van Atta Retrodirective Arrays

As the front end of RF system,antenna plays an important role of receiving or transmitting electromagnetic signals.Its performance directly affects the quality of RF signals in the system.As a special phased antenna array,retrodirective array has been widely researched because of its characteristic of automatically tracking incoming wave when the specific information of incoming wave is unknown.As an important form of retrodirective array antenna,Van Atta array is famous for its compact and simple structure,planarization and easy conformal,and low cost.This thesis studies wide-angle Van Atta retrodirective array based on the basic principle of differential pattern.The bending conformal condition of Van Atta array is briefly analyzed.The main research content is divided into the following three parts:Firstly,based on the phase conjugate principle,the negative effects of array size,feed network and substrate dielectric materials on far-field RCS in a direct-fed Van Atta retrodirective array are verified.The retrodirective array takes single microstrip antenna and serial-fed array as the retrodirective unit,which has obvious retrodirective effect compared with the metal plate with equal area.However,in the direction far away from the main radiation,the scattered field generated by the structure and other factors cancel the retrodirective field,resulting in great attenuation.Therefore,this structure has great limitations in application,but lays a foundation for the subsequent structural improvement.Secondly,a wide angle Van Atta retrodirective array based on coupled feed is studied.The array realizes wide-angle retrodirective in a wide band based on the differential pattern and coupled feed,and it uses the feed network attached to the bottom to reduce the far-field RCS scattering component to further improve the retrodirective effect.The design is simulated for 1×4 arrays.The simulation results show that the beamwidth of-3d B RCS is 120°,but the whole RCS beam curve fluctuates obviously due to the small gain of the unit.Using 1×4 array as subarray,4×8 array is obtained for simulation and measurement.The-3d B RCS beamwidth obtained by the simulation of the 4×8 array is116°,and the-3d B RCS beamwidth obtained by the measurement is 120°.The RCS beamwidth of the 4×8 array is improved in the direction away from the main radiation due to the increasement of the overall gain.Thirdly,a wide-angle Van Atta retrodirective array based on high-gain elements is designed to solve the problem that the antenna element gain is insufficient in the design of wide-angle Van Atta retrodirective array based on coupled feed,which causes obvious fluctuations in far-field RCS.The array still realizes wide angle retrodirective based on the principle of differential pattern and phase conjugation.The-3d B RCS beamwidth obtained by the simulation of array is 116°,the final measurement result is 115°,which has a good agreement with the simulation result.