Research On Key Technologies In Beam Forming Of Frequency Diverse Array

Frequency Diverse Array(FDA)employs a small frequency offset on the transmit carrier frequency of each array element,so that its beampattern is 'S' shaped in the range-angle plane,showing characteristics as range-angle coupling,periodic,automatic scan-ning,etc.Aiming at the key characteristics of time-varying,periodicity and range-angle correlation of the FDA transmit beam,this thesis conducts in-depth research on its trans-mit beam forming and application method,mainly including the range-angle decoupling method of the FDA transmit beam? an FDA transmit beamforming method for interfer-ence suppression? and an error analysis method for an FDA in beamforming.The main research work and innovation points are as follows:(1)Research on the range-angle decoupling method of FDA transmit beams: Aiming at the range-angle coupling problem of the FDA beams,this thesis proposes a frequency offset coding algorithm based on Taylor window function,which breaks the linear incre-mental frequency offset rule,re-encodes the frequency offset loaded by each element of the FDA,and then obtains a new frequency offset vector based on the Taylor window.At last,the purpose of range-angle decoupling of the beampattern can be achieved by using the optimized frequency offset vector.(2)Research on FDA transmit beamforming methods for interference suppression:For the application scenario of FDA for interference suppression,this thesis proposes two FDA transmit beamforming methods for interference suppression? the first method mainly aimed at the situation where the interference position is known.By designing the zero position of the general polynomial,where the zero position is the position of the interference source,the transmitting beam expression of the FDA is optimized,and then the zero power point can be formed at the given interference source position,so as to suppress the interference at the known position? the second method is mainly aimed at the situation of unknown interference position.The Chebyshev polynomial is used to optimize the beam of the FDA,and then the sidelobe level of the FDA beam is suppressed to a set low value,which can reduce the unknown interference energy in the sidelobe region and achieve the effect of suppressing the interference of unknown position.(3)Error analysis of FDA beam: Aiming at the possible error problem in beamform-ing of FDA,this thesis proposes an improved error analysis method based on interval algorithm(IA),and applies it to the analysis of the frequency offset error and element position error of the FDA,the method first assumes that the frequency offset error or the element position error of the FDA exists in a known interval,and then it can be converted into the corresponding phase error interval,after that uses the improved interval division rule to obtain the interval midpoint and width value,and finally substitute into the derived FDA error model based on the improved interval algorithm.At last,the upper and lower bounds of the beam caused by the error can be obtained.By using the upper and lower bound values of the obtained beam error interval,the possible influence of frequency offset or array element position error on the beam performance can be analyzed accordingly.