Research On Some Key Technologies Of Wideband Array Transmitting Antenna

With the rapid development of high-tech advanced weapons,modern electronic warfare is facing great challenges.Wideband digital array technology plays an important role in electronic warfare system.This dissertation focuses on three key technologies involved in wideband digital array transmission system,the antenna array design,the finite linear dynamic range of the transmitting antenna RF(radio frequency,RF)power amplifier and the phase error in the array channel are studied.In this dissertation,the key technical difficulties of the wideband array transmitting system are analyzed,solutions are proposed,and the improvements of the solutions are verified by simulation.In this thesis,we mainly study the design of wideband array,the optimization of the linear dynamic range of the RF power amplifier,the method of suppressing the large PAPR(Peak to Average Power Ratio,PAPR)in the multi-channel signal synthesis,and the method of correcting the phase error in the channel of the antenna element.Its specific research ideas and contents are as follows:1.In order to solve the problem of wideband array design,this paper subdivides it into wideband linear array and planar array.In this paper,the method of sparse array is used to design linear array,and the method of sparse array is used to design area array.In order to solve the problems of decreasing the main lobe gain and increasing the side lobe of the antenna pattern in the broadband linear array,the array factors of the sparse linear array are optimized,and the global optimization model is optimized by using the heuristic,the optimized element position distribution and the optimized antenna pattern are obtained.However,there are different degrees of local optimization in traditional heuristic,which leads to poor optimization results.In order to obtain a better global optimization solution,three heuristic are improved in this paper.In this paper,genetic algorithm is improved by naive bayes method,simulated annealing algorithm is improved by adaptive factor,and particle swarm optimization algorithm is improved by weighted oscillatory factor method.In the experimental section,the three improved algorithms are verified and compared,and their respective characteristics are analyzed and summarized.When designing the sparse array,the algorithm can be flexibly selected according to the actual hardware conditions to obtain the suitable antenna array element position distribution.In order to avoid the use of dense uniform subarray and reduce the mutual coupling effect,an improved dense subarray design method is proposed in this paper.In the improved design method,the element positions in the dense subarray can be arranged according to the coprime sequence pairs or the minimum redundant sequence pairs,which effectively reduces the element density of the dense subarray.At the same time,the size and the degree of freedom of the antenna array can be further optimized by adding additional elements and optimizing the distance between subarrays.2.In the problem of linear dynamic range of RF power amplifier,the optimization of linear dynamic range of RF power amplifier and the suppression of multiple superimposed PAPR(Peak-to-Average Power Ratio,PAPR)are researched in this dissertation.Aiming at the problem of limited linear dynamic range in power amplifier,the nonlinear pre-transformation method can be used to counteract the nonlinear variation in power amplifier.However,the present nonlinear pre-transformation algorithm has some problems such as low precision of coefficient estimation.In this paper,RLS(Recursive Least Squares,RLS)is used to estimate the coefficients of the nonlinear model.Compared with the traditional nonlinear model,the accuracy of coefficient estimation is higher,and the algorithm can cancel the nonlinear transformation accurately.In order to solve the problem of large PAPR of multi-sub signals in the array channel,the pre-distortion method and the non-predistortion method are studied in this paper.For serious signal distortion caused by pre-distortion,pre-coding method is used to reduce the correlation between signals.At the same time,this paper presents a limit method of conformal transformation based on look-up table.The conformal transformation is carried out to obtain the limiting effect.Because of the look-up table,this method can achieve fast transformation results.In the non-predistortion method,this paper presents a blind selective mapping method based on MUSIC algorithm.The synthesized signal is decomposed by QR of the Matrix,and the number of the phase sequence is expanded,then the synthesized signal is decomposed by MUSIC algorithm,and the signal sequence with the lowest PAPR is selected by judging the degree of orthogonality between the signal subspace and the noise subspace.This algorithm avoids the transmission of sideband information,improves the utilization ratio of frequency band,and reduces the computational complexity.3.For the phase errors in the channel of the array element,the issue is divided into the phase error correction of the aperture transition effect of the wideband signal,the phase error correction of the external noise interference signal and the phase error correction of the physical reason of the array element.In view of the phase error caused by the aperture transition effect,the time-delay network is used to pre-emphasize the phase of the signals in each channel.In the correction of phase error caused by external noise interference,STFT transform method based on full pole window function is used,which can obtain more accurate results of signal separation.The delay factor method is used to estimate the phase correction matrix at a finite number of sampling frequency points.Then,the coefficients of the grouped FIR filters are fitted according to the adaptive factor least squares,and the phase correction of all the frequency points in a wide band is realized.The algorithm improves the correction accuracy of general algorithm and simplifies the complexity.