Clutter & Jamming Suppression And Performance Evaluation Of Airborne Early Warning Radar

With the development of science and technology,the requirement of airborne warning and control system(AWACS)in modern warfare is increasingly high.The problems of high cost and manned need have gradually emerged.In recent year,unmanned aerial vehicle(UAV)becomes a popular platform of AWACS due to its advantages such as cheap cost and well concealment.However,high-altitude long-endurance UAV(HALE-UAV)takes more consideration of the flight performance rather than the load,which causes the difficulty to install large phased array radar.One solution is to install the antenna on the lower surface of airfoil,which can gain large antenna area.Besides,the airborne radar is inevitably affected by ground clutter and interferences,which seriously affect the target detection ability of radar.Therefore,suppression methods need to be studied.Existing researches of clutter suppression,interferences suppression and performance evaluation mainly focus on vertical or nearly vertical array rather than horizontal array,so it's necessary to do some research.This thesis mainly focuses on the clutter and interferences suppression and performance evaluation of airborne early warning radar using horizontal array.Firstly,a clutter model of three-dimensional array is provided.Clutter characteristics and space time adaptive processing(STAP)are studied.A sub-array synthesis way of horizontal array is given.Secondly,a new interference suppression method based on notch filter is proposed.Thirdly,a fast method is given to solve the problem of large computation in pulse repetition frequency selection.The beam design method and the calculation method of radar detection distance are improved.The work of this thesis is outlined as follows:1.Clutter signal model and clutter suppression method are studied.Signal model of horizontal array is different from vertical array.Firstly,the clutter model of three-dimensional array is provided and the clutter characteristic of horizontal array is analyzed.Secondly,some normal reduced-dimension STAP methods are performed in order to verify the effectiveness of these methods.Finally,a sub-array synthesis way of horizontal array is given.2.Interference suppression methods are studied.Based on the analyses of narrow-band continuous interference and asynchronous short-pulse interference,the signal models are given.Two suppression methods are given to suppress the narrow-band continuous interference and the characteristics of the methods are analyzed.A new method which has fast processing speed and low calculation is proposed to suppress the asynchronous short-pulse interference and the effect of the method is verified by simulation.3.Parameters design and performance evaluation methods are studied.Usually the performance of radar is decided by its parameters,such as beam sequence and pulse repetition frequency.Therefore,it's important to design the parameters of radar before performance evaluation.In this thesis,the beam design method is improved to fit the horizontal array condition.A fast pulse repetition frequency design method is given to reduce the computation.In order to reduce the error,the effective of atmospheric attenuation is considered when calculate the radar detection range.Finally,the performance evaluation method and error calculation formulas are summarized.