Research On Wideband Antenna Array And Direction Finding Algorithm

With the improvement of the bandwidth and rate of communication equipment,the research and application of broadband antennas and arrays have been paid more and more attention by researchers.The thesis studies the wideband array antenna and direction finding algorithm technology.Combining the antenna array and direction finding algorithm technology effectively improves the direction finding ability of the direction finding algorithm in the wideband array.In this thesis,based on the analysis of the design principles and solutions of the omnidirectional disk cone antenna in the time domain,the double-layer circular plate and the end of the cone are bent to carry out broadband matching and miniaturization research and design,so that it can obtain good Radiation and matching characteristics.Furthermore,the time domain solution method was used to analyze and simulate the time domain characteristics including time domain transmission characteristics,time domain reception characteristics,group delay,signal fidelity,and amplitude-frequency and phase-frequency characteristics.In order to meet the technical needs of ultra-wideband systems,a volcanic smoke-like monopole antenna capable of horizontally and omnidirectionally receiving radar signals from 0.8?18 GHz has been designed.The result can achieve VSWR?2.5 and good omnidirectional radiation performance in the whole frequency band.In order to verify its performance,the principle prototype was tested on the ultra-wideband antenna system,and the test results were basically consistent with the simulation results.For the needs of broadband direction finding arrays,a miniaturized printed log-period dipole antenna was designed.By bending the antenna element arm twice,the lateral size of the printed log-periodic dipole antenna is effectively reduced by 37.6%.The bending angle,spacing and length of each arm after bending are analyzed and optimized reasonably,and finally VSWR?2.5 and good beam characteristics can be achieved at 0.4?1.5GHz.According to the design requirements of the direction finding algorithm,the directional antenna of the 8-element wideband circular array is analyzed and studied.The designed miniaturized broadband directional antenna array is combined with the comparing amplitude algorithm and its directional accuracy is improved.Firstly,the eight-element comparing amplitude algorithm is introduced.According to the characteristics of the ring array signal,the system error and random error of the omnidirectional amplitude direction finding were simulated and calculated,and the results of beam width error,opening angle error and channel imbalance error were analyzed and summarized using MATLAB.In addition,the MUSIC algorithm based on spatial spectrum estimation is studied,and the processing method when the signal is a wideband signal or a coherent signal is analyzed.Simulation results of the ideal result are also calculated.By changing the SNR,the number of incoming waves and the number of sampling times,the performance of the DOA of the MUSIC algorithm in various cases is compared.Then,a miniaturized printed log-period dipole antenna was used to design an 8-element wideband direction finding array.The designed direction finding antenna array can achieve VSWR?2.5 in 0.4GHz?6GHz,isolation is greater than 30d B,and the radiation characteristics in the whole frequency band are good,and the beam crosspoint loss is large L_s?2.1 d B.In order to verify the actual performance of the designed broadband ring array,the principle prototype was processed and tested.The test results were basically consistent with the calculation results.Finally,the designed omnidirectional comparing amplitude algorithm was simulated and verified using the designed 8-element wideband circular array.The results show that the direction finding error at whole wideband is ??<3.4°(RMS).