Research On Wideband Wide-Angle Scanning Tightly Coupled Phased Array Antennas

Phased-array antennas are widely used in communication and radar fields due to their high scanning speed,high directivity and high accuracy,and the research enthusiasm has been rising in recent years.With the increasing demand for high performance and high reliability antenna system,it makes the phased array antenna develop towards wider bandwidth and wider scanning angle range.It becomes a challenge to design the antenna to meet the requirements of ultra-wideband large-angle scanning performance while the requirements of simple structure,low profile,and low cost are taken into account.In this thesis,from the mutual coupling,the design method of tightly coupled ultra-wideband wide-angle scanning phased-array antenna is investigated mainly as follows:1.Combined with the equivalent circuit diagrams of the tightly coupled array antenna in free space and with ground,their active input impedance are derived,and the results of full-wave simulation software and circuit simulation software are compared to verify the accuracy and rationality.The effects of ground and critical structural parameters on their input impedance are discussed to provide reference for the subsequent design of ultra-wideband wide-angle scanning array antennas.2.A tightly coupled ultra-wideband wide-angle scanning phased array antenna based on the dipole antenna is designed.In this design,to ensure the ultra-wideband characteristics of the antenna and to complete the unbalanced to balanced structural conversion,the feed adopts a hyperbolic tapering impedance converter structure and uses shorting strips to move the common-mode resonance frequency out of the high limit inside operating band.The performance of three kinds of matching layers-a dielectric layer,a frequency selective surface(FSS)and a zigzag metasurface,are compared,and a design idea of wide-angle impedance matching(WAIM)layer sharing the same dielectric substrate with the antenna array is adopted,which has the advantages of simple processing,easy installation and so on.The performance of an 8×8 array is verified by using the full wave simulation software.Finally,the size of the antenna array is 0.8λ_L×0.8λ_L,and the total profile is 0.15λ_L(λ_L is the wavelength corresponding to the lowest operating frequency).Subject to active VSWR<2.9,the antenna array can achieve a beam-scanning range of±60°in E-plane and H-plane with4.26:1 bandwidth.3.A tightly coupled ultra-broadband wide-angle scanning phased array antenna based on the connected slot is designed.This prototype array exhibits a 2.06:1bandwidth out toθ=±60°in E and H planes,with a total profile of 0.069λL.In this design,a parasitic dual slot is introduced to reduce the input impedance of the tightly coupled array antenna,allowing it to be fed directly using a coaxial interface,avoiding the complex feeding network design.The wide-angle matching layer is integrated on the antenna array surface to achieve low profile and light weight,and the multi-segment metal strips are used to improve the freedom and adjustable range.The equivalent circuit model of the connected triple-slot antenna array is established and verified by the full-wave simulation results.The performance of the one-dimensional infinite array is simulated to verify the correctness of the design.