Study On The Key Technology Of Retrodirective Antenna

With Internet of Everything(IoE)coming,wireless communication technology is facing a number of challenges like increased number of users,limited bandwidth,communication capacity and so on.The antenna is the bottle-neck of the wireless communication system,as it is the RF front-end device.There is an urgent need for novel antenna arrays with a compact structure,low cost,high gain and self-beam steering for better communication applications.Retrodirective antenna array can achieve beam-steering by phase conjugation and when compared with smart antenna and phased array antenna,the retrodirective antenna has the ability to transmit the signal back to the source without prior knowledge of the incoming signal information and sophisticated digital processing,therefore showing great prospects in wireless connection system technologies.Firstly the article summarizes basis of retrodirective antenna and research overview at home and abroad.Conformal characteristics,multiple-direction response and Doppler effect of this antenna are also analyzed and simulated.Later two of the innovative methods are proposed and verificated to solve the beam pointing error of retrodirective antenna in dual-frequency systems.One method is the beam pointing compensation based on beam space pre-identify.The phase compensation is related to arriving angle,and the possible range of the arriving angle could be estimated by transformation from array space to beam space,based on which the phase compensation can be determined and beam pointing error can be reduced.Simulation results demonstrate that the proposed method is able to reduce beam pointing error by almost an order of magnitude with strong robustness over Gaussian white noise.Another method is gain compensation based on pattern synthesis.The main beam is broadened among the beam pointing error range by optimizing the element weights.Therefore,the gain loss induced by beam pointing error is reduced.Simulation results show improvement in gain compared to traditional retrodirective antenna.Finally,the information leakage of retrodirective in self-steering mode is studied.The signal-to-noise ratio suppression based on noise null steering,and beam control based on sub-array phase,are analyzed and testified.In the first method,noise modulating device is introduced making the noise pattern null in arriving angle.The noise radiation will cause interference in other directions therefore changing the signal to noise ratio in order to ensure information security.In the second method,retrodirective antenna plays as a sub-array,nulling of array pattern is steered by controlling phase among the sub-arrays and response in a certain direction is suppressed.The improved array can achieve self-tracking as well as beam controlling.