Studies On Key Techniques Of Ultra-Wide-Angle Scanning Multi-beam Lens Antennas

Dielectric lens antennas are widely used in telemetry,remote sensing,aerospace communications,ship communications,satellite communications and 5G communications,due to their features such as the remarkable antenna focusing performance,high gain,multi-beam scanning,and low cost.With the rapid development of communication and other industries,more and more application scenarios require multi-beam antennas to have the capability of wide-angle beam scanning.This thesis has carried out related research work on the ultra-wide angle scanning technology of lens antennas and key techniques in the design and implementation process.The main contents include:Firstly,the research background and application scenarios of lens antenna technology,especially Luneberg lens antenna technology are described,and the development history and latest research trends of lens antennas are reviewed.Secondly,the basic principles of lens antennas and Luneberg lens antennas are introduced,and the theoretical analysis of lens antennas and Luneberg lens antennas based on geometrical optics theory is discussed.The principle of transformation optics and quasi-conformal transformation optics theory is deduced and analyzed through formulas and equations,and the effective medium theory required in the lens design and processing is reviewed to realize the effective replacement of low dielectric constant media.Thirdly,the studies on ultra-wide angle scanning,low-profile,multi-beam flat-lens antenna technology are presented.By using transformation optics and quasi-conformal transformation theory to compress a cylindrical Luneberg lens,a transformed Luneberg lens is designed.This lens has the same functions as a cylindrical Luenberg lens and can be fed using a linear feed array.A flat-panel lens antenna designed for beam scanning based on linear array feeding in the K/Ka band was designed.The antenna achieves a wide-angle scanning range of-63°~63°(with adjacent beams overlapped at-3dB-level)in the azimuth plane,the maximum gain is higher than 15 dBi,and the gain decreases less than 3.3dB at the maximum beam scanning angle.Fourthly,a circularly polarized Luneberg lens antenna is designed for a half-space beam coverage in the 7.7GHz to 8.2GHz band.This antenna can achieve beam scanning coverage in the range of-90°~90°(with adjacent beams overlapped at-3dB-level),and the azimuth plane is 360 ° omnidirectionally scanned.The beams cover the upper half space while the gain for each beam is higher than 11 dBi.In the design process,key technologies such as the compact feed antenna,array optimization,and effective medium Luneberg lens design based on the effective medium theory are studied.Finally,the fabrication method and test method of circularly polarized Luneberg lens antenna for the half-space beam coverage are introduced.The feed antennas are manufactured by a multilayer PCB process,with small size and compact structure.The lens and holder are processed by 3D printing technology.As compared to traditional mechanical fabrication methods,3D printing technology has the advantages of low cost and short processing time.After Assembling and testing the antenna prototype,measurement results are found to be in good agreement with the simulation results,thus showing remarkable antenna performance.