Broadband Beamforming Technology Based On Metamaterial Electromagnetic Len

Broadband signal has gradually become the main signal form used in modern radar and communication systems because of its large amount of information,strong anti-jamming ability,radar resolution and high communication rate.Therefore,broadband beamforming has become a research hotspot.Conventional broadband beamforming technology based on array signal processing can form accurately pointing beams,but it has the disadvantages of large amount of calculation and high hardware cost.Metamaterial electromagnetic lens has energy focusing characteristics based on spatial angle.Combined with antenna array,it can form high gain broadband beam.It has the advantages of low cost,low power consumption and easy engineering implementation.The main contents of this thesis include:Based on the study of the beamforming theory of narrowband array antenna,the influence of aperture transition phenomenon on broadband signal beamforming is analyzed,the basic methods of broadband beamforming and adaptive beamforming are studied,and the advantages and disadvantages of broadband beamforming methods in frequency domain and time domain are discussed.Based on the generalized Snell’s law,the design method of metamaterial electromagnetic lens is studied.By designing the phase distribution of metamaterial surface,a high gain beam is formed.A metamaterial electromagnetic lens is designed by using the equivalent circuit method.The amplitude frequency response characteristics and phase frequency response characteristics of the lens unit are controlled by changing the size of the metal patch and the linewidth of the metal grid.CST simulation data show that the designed lens unit has good amplitude frequency response within the working frequency and can supply power,and the magnetic wave can be transmitted almost losslessly.The electromagnetic lens of each size has good phase gradient characteristics,which means that the electromagnetic lens can be formed by reasonably arranging the electromagnetic lens units,which lays the foundation for the following broadband beamforming using the electromagnetic lens.The array broadband beamforming technology loaded with metamaterial electromagnetic lens is studied,the energy focusing characteristics of electromagnetic lens based on spatial angle are analyzed,and the overall structure design and parameter setting method of millimeter wave band dual period electromagnetic lens are proposed.The mathematical model of the array loaded with electromagnetic lens is constructed.Based on the requirements of broadband multi beam scanning,the mechanism of realizing continuous beam free scanning of the array is discussed,and an optimization method based on beam pattern synthesis is proposed.The main optimization goal is to make the weighted antenna array beam pattern approach the reference beam pattern as much as possible,and successfully realize the multi beam forming of loaded electromagnetic lens array.In order to further reduce the cost and power consumption of the array system loaded with electromagnetic lens,a multi beam optimization design method based on trade-off factor is proposed.On the premise of ensuring that the formed beam accurately points to the preset desired direction,the number of antenna array elements can be minimized,and the cost and power consumption of the whole antenna array system loaded with lens can be greatly reduced,Simulation results show the effectiveness of the proposed algorithm.