A method to design a beamformer for broadband constant beamwidth is presented. Constant beamwidth is important in sonar systems for sea bottom observation and classification applications. For a given frequency band, a...A method to design a beamformer for broadband constant beamwidth is presented. Constant beamwidth is important in sonar systems for sea bottom observation and classification applications. For a given frequency band, a number of frequency points are chosen to represent the response of an arrary element. For each frequency point a beamforming weight vector can be deduced to satisfy the given beamwidth requirement by existing methods. Therefore, for a broadband array of N elements, each row of the N' M weighting matrix represents the frequency response of an element of the array which can be satisfied by a FIR filter designed by model - reference adaptive technique. The sum of outputs from a bank of N FIR filters provides a beamformed output and so it is very handy to be implemented by DSP hardware.展开更多
A new method of broadband constant beamwidth beamforming for arbitrary ge- ometry arrays is proposed. In this method, the response vector of an arbitrary geometry array is expanded into the form of sum of an infinite ...A new method of broadband constant beamwidth beamforming for arbitrary ge- ometry arrays is proposed. In this method, the response vector of an arbitrary geometry array is expanded into the form of sum of an infinite series, whose core function is the first kind Bessel function. The high terms of this series are truncated so that the array response vec- tors at different frequencies can be transformed to a reference frequency and then the constant beamwidth beamforming vectors are ready to obtain. With these beamforming vectors, beams at different frequencies are same as the reference beam. A reference beam optimizing method based on adaptive processing is also proposed to optimize the reference beam of arbitrary ge- ometry arrays. Computer simulation for a uniform circular array verified the effectiveness of the new method proposed.展开更多
Side lobe level reduction(SLL)of antenna arrays significantly enhances the signal-to-interference ratio and improves the quality of service(QOS)in recent and future wireless communication systems starting from 5G up t...Side lobe level reduction(SLL)of antenna arrays significantly enhances the signal-to-interference ratio and improves the quality of service(QOS)in recent and future wireless communication systems starting from 5G up to 7G.Furthermore,it improves the array gain and directivity,increasing the detection range and angular resolution of radar systems.This study proposes two highly efficient SLL reduction techniques.These techniques are based on the hybridization between either the single convolution or the double convolution algorithms and the genetic algorithm(GA)to develop the Conv/GA andDConv/GA,respectively.The convolution process determines the element’s excitations while the GA optimizes the element spacing.For M elements linear antenna array(LAA),the convolution of the excitation coefficients vector by itself provides a new vector of excitations of length N=(2M−1).This new vector is divided into three different sets of excitations including the odd excitations,even excitations,and middle excitations of lengths M,M−1,andM,respectively.When the same element spacing as the original LAA is used,it is noticed that the odd and even excitations provide a much lower SLL than that of the LAA but with amuch wider half-power beamwidth(HPBW).While the middle excitations give the same HPBWas the original LAA with a relatively higher SLL.Tomitigate the increased HPBWof the odd and even excitations,the element spacing is optimized using the GA.Thereby,the synthesized arrays have the same HPBW as the original LAA with a two-fold reduction in the SLL.Furthermore,for extreme SLL reduction,the DConv/GA is introduced.In this technique,the same procedure of the aforementioned Conv/GA technique is performed on the resultant even and odd excitation vectors.It provides a relatively wider HPBWthan the original LAA with about quad-fold reduction in the SLL.展开更多
文摘A method to design a beamformer for broadband constant beamwidth is presented. Constant beamwidth is important in sonar systems for sea bottom observation and classification applications. For a given frequency band, a number of frequency points are chosen to represent the response of an arrary element. For each frequency point a beamforming weight vector can be deduced to satisfy the given beamwidth requirement by existing methods. Therefore, for a broadband array of N elements, each row of the N' M weighting matrix represents the frequency response of an element of the array which can be satisfied by a FIR filter designed by model - reference adaptive technique. The sum of outputs from a bank of N FIR filters provides a beamformed output and so it is very handy to be implemented by DSP hardware.
基金the National Natural Science Foundation of China (No. 69802010).
文摘A new method of broadband constant beamwidth beamforming for arbitrary ge- ometry arrays is proposed. In this method, the response vector of an arbitrary geometry array is expanded into the form of sum of an infinite series, whose core function is the first kind Bessel function. The high terms of this series are truncated so that the array response vec- tors at different frequencies can be transformed to a reference frequency and then the constant beamwidth beamforming vectors are ready to obtain. With these beamforming vectors, beams at different frequencies are same as the reference beam. A reference beam optimizing method based on adaptive processing is also proposed to optimize the reference beam of arbitrary ge- ometry arrays. Computer simulation for a uniform circular array verified the effectiveness of the new method proposed.
基金Research Supporting Project Number(RSPD2023R 585),King Saud University,Riyadh,Saudi Arabia.
文摘Side lobe level reduction(SLL)of antenna arrays significantly enhances the signal-to-interference ratio and improves the quality of service(QOS)in recent and future wireless communication systems starting from 5G up to 7G.Furthermore,it improves the array gain and directivity,increasing the detection range and angular resolution of radar systems.This study proposes two highly efficient SLL reduction techniques.These techniques are based on the hybridization between either the single convolution or the double convolution algorithms and the genetic algorithm(GA)to develop the Conv/GA andDConv/GA,respectively.The convolution process determines the element’s excitations while the GA optimizes the element spacing.For M elements linear antenna array(LAA),the convolution of the excitation coefficients vector by itself provides a new vector of excitations of length N=(2M−1).This new vector is divided into three different sets of excitations including the odd excitations,even excitations,and middle excitations of lengths M,M−1,andM,respectively.When the same element spacing as the original LAA is used,it is noticed that the odd and even excitations provide a much lower SLL than that of the LAA but with amuch wider half-power beamwidth(HPBW).While the middle excitations give the same HPBWas the original LAA with a relatively higher SLL.Tomitigate the increased HPBWof the odd and even excitations,the element spacing is optimized using the GA.Thereby,the synthesized arrays have the same HPBW as the original LAA with a two-fold reduction in the SLL.Furthermore,for extreme SLL reduction,the DConv/GA is introduced.In this technique,the same procedure of the aforementioned Conv/GA technique is performed on the resultant even and odd excitation vectors.It provides a relatively wider HPBWthan the original LAA with about quad-fold reduction in the SLL.
