The Study On Beam Pattern Broadening Technology In Short Wave Array Systems

Short wave can be used for long-distance propagation with less power by ionospheric reflection.With many desirable advantages,e.g.,long transmission distance,not easy interference,etc.,short wave is widely used in modern communication and radar systems.Especially in modern electronic warfare,the reconnaissance and jamming of short wave systems is an important research direction.The increasing complexity of the electromagnetic environment in battlefield brings more requirements for space coverage capabilities and targets tracking capabilities of electronic reconnaissance and jamming systems.Hence,beam broadening is necessary to be carried out for the array-based reconnaissance and jamming systems of short wave systems to enhance the efficiency of array scanning as well as improving the target coverage and tracking capabilities.To handle the issues,this thesis studies the beam broadening technology employing different methods in the short wave frequency band under different array structure conditions.The main contents of this thesis are listed as follows:For the needing of beam broadening of uniform linear array,the basic principle of beam forming is first described.The phase weighting and amplitude-phase combination methods are studied for beam broadening of the uniform linear array.Furthermore,the beam patterns are compared with beam broadening or not,at different shortwave frequency points for given array structures.Finally,the characteristics of corresponding beam broadening methods are analyzed in detail based on the simulation results.For the needing of beam broadening of uniform circular arrays,omnidirectional and half-wave array elements are considered separately.Firstly,the simulation results of beam broadening of antenna pattern using Kaiser,Chebyshev,and Blackman windows are obtained,and the applicable scope of the three window-broadening methods is obtained.Secondly,by selecting the expected response error norm,the optimal solution of beam pattern is obtained based on the least mean square criterion,and this antenna pattern is satisfied with broadening requirements naturally.Furthermore,the critical radiuswavelength ratio is obtained with a series of simulations by adjusting the array frequency in the beamforming.The empirical suggestions can be used to guide engineering practice.Since large-scale array deployment has high hardware costs,the beam-broadening technology of non-uniform circular arrays is studied in this thesis.Specifically,the nonuniform circular array is designed by random array layout,angle segmentation,and random selection of continuous array elements.Furthermore,the beam-broadening and beam-shaping methods are used respectively to obtain the antenna pattern.Moreover,a series of simulation experiments are implemented at different frequencies.Finally,the suitable critical radii wavelength ratio of the beam forming method and application suggestions of the beam broadening technology under different non-uniform circular arrays obtained from simulations can guide engineering practice in corresponding application scenarios.