Pattern Synthesis For Digital Antenna Arrays

Compared with the traditional phased array,digital antenna array is a newer phased array architecture.Due to its superiority of all-digital processing,it has a larger dynamic tolerant range.With digital beamforming(DBF)and pattern synthesis technology both in transmitting and receiving arrays,better antenna beam performance can be obtained,which means less energy loss and a lower sidelobe.Thereby it has a more excellent system detecting、target tracking and satellite communication ability.Therefore,more and more researchers around the world are paying attention to the digital antenna array.Based on the practical requirements of arbitrary pattern synthesis with digital array antenna、phase-only control and LEO satellite-borne multi-beam pattern synthesis with isoflux coverage and so on,this article has carried out the research on arbitrary array pattern synthesis algorithm、the joint pattern synthesis of transceivers,technology of multi-beam pattern synthesis with isoflux coverage and subarray phased array simultaneous multi-beamforming.The main contents can be summarized as follows:1.A new array synthesis method based on the alternating projection(AP)and proximal splitting is proposed(WAPPS).The proposed method takes the difference of the element pattern in the array into account.Under the framework of AP,the projector over excitation constraints is designed as the solution to a Constrained Weighted Least Mean Square(CWLMS)optimization problem.Then an effective proximal splitting method is developed to solve the CWLMS optimization using proximity operator theory,which can obtain the arbitrary array pattern with continuously adjustable excitation amplitude and phase.Compared with traditional AP algorithm and Weighted Alternating Reverse Projection method(WARP),the proposed algorithm can obtain better beam performance and convergence speed.2.A new method of fast pattern synthsis is presented in this paper.Under the framework of AP method,the amplitudes of desired pattern is firstly constrained.Then the method adopts an auxiliary phase function to obtain the optimized phased of desired pattern.Finally,the required excitations can be obtained from a CLMS,which is solved by the proximal splitting method.Compared with other methods based on AP,the optimization of pattern phase is helpful to improve the convergence speed and performance of the algorithm.The synthesized results show its high performance in the pattern synthesis with or without excitation constraints.The proposed method is suitable for the arbitrary arrays and has good generalization capability.3.A new synthesis algorithm for arbitrarily shaped patterns with adjustable excitations,generated by transmitting and receiving arrays is proposed in this article.Sometimes,it’s hard to obtain the satisfying transmit and receive patterns respectively,especially when the transmitting array needs to work at full power.In this case,jointly optimizing the transmitting and receiving patterns can be considered,which makes the transceiving performance meets the demands.Therefore,for this kind of joint optimization problem,according to the radar range equation,the authors vividly present the definition of the joint pattern of the transceiving array(JPTS)first.Then,a new synthesis method for JPTS with adjustable excitations is proposed.In general,the proposed method not only can obtain the better synthesized pattern,also can reduce the difficulty of pattern synthesis.4.An optimization approach is proposed to generate LEO satellite-borne multiple patterns with isoflux coverage.The purpose is to find a common amplitude distribution and different phases corresponding to the different patterns.The common amplitudes are with several levels,which are calculated adaptively in the iteration.In addition,this method takes the problem of the large under-satellite difference in LEO satellite communication into account.By using pattern synthesis techniques,the isoflux coverage with multi-beam can be achieved,so that the receiving gain can be basically consistent.5.A method for simultaneous multibeam pattern synthesis based on subarray phased array is proposed.This method not only optimizes the excitation of each element,but also obtain the subarray weights which can simultaneously output multiple beams that meet the synthesis requirements under the condition that the element excitation vector remains unchanged.Compared with pattern synthesis with only subarray,the synthesis freedom is increased.Compared with multibeam pattern synthesis with only element antennas,the number of AD channels decreases which can reduces the hardware cost.Firstly,construct multiple output beams into an output matrix,and perform F-norm approximation with the target pattern matrix.Then by using the properties of Kronecker product and Khatri-Rao product,rewrite the F-norm approximation into a two-norm approximation to solve the problem.Finally the temporary target pattern is cyclically modified to obtain the satisfied element weight vector and subarray weight matrix.