Research On The Key Technologies Of Tightly Coupled Low-profile Wideband And Wide Angle Scanning Phased Array

With the further development of radar and communications technology,the application scenarios of phased array antennas are increasing.Phased array antenna technology needs to be continuously improved and developed.In electronic systems such as communications and radar,the antenna array structure and the design of its T/R components are the key structures of the overall design and the core technology to ensure the systems performance.At the same time,more application scenarios and complex electronic systems have placed increasing demands on the performance of phased array antennas.Wide frequency band,higher gain,lower side lobe,lower cross-polarization level,lower profile,more beams,and faster beam steering are all higher performance requirements for the array.These require phased array antenna designers to devote more efforts to design methods,structural complexity,and electrical characteristics of feeding network in order to find better performance.While improving and ensuring the key performance of phased array antenna just like bandwidth and scanning characteristics,improving its adaptability,reducing profile and simplifying structure has become the main direction and key issue for the development of phased array antennas.This thesis explores and discusses how to implement low profile designs with wide-band and wide-angle scanning.The main investigated and discussed contents are as follows:In the first chapter,we mainly introduce the background and significance of the research.Two types of phased array antennas and the research status of tightly coupled phased arrays at home and abroad are introduced.In the second chapter,we introduce the basic theories and key technologies of the tightly coupled phased array antenna.The basic theories include the directivity,mutual coupling of elements,pattern synthesis and scanning pointing principle,and the key technologies include the coupling structure,wide angle matching layer and balun.In addition,the detailed analysis of the tightly coupled phased array theory is introduced in detail.In the third chapter,based on the key structure,a design of tightly coupled phased array unit that can achieve wide-band and wide-angle scanning while maintaining low profile is introduced.The simulation is performed by simulating infinite array with periodic boundaries.The simulation results show that the bandwidth of the antenna is 2.4-4.2 GHz with its|S₁₁|less than-10 dB,achieving a bandwidth of 1.75:1.At the same time,it can be seen from the VSWR that the scanning performance of E-plane is better than that of H-plane.The scanning range of the E-plane can achieve a maximum of±75°while maintaining the VSWR less than 3,while that of the H-plane achieves up to±60°.In the fourth chapter,a 2×8 tightly coupled phased array antenna is designed by using the antenna element proposed in Chapter 3.It can realize the E-plane scanning.In order to maintain the scanning performance of the array,the floor size is enlarged.The simulation and test results show that the array has a good one-dimensional scanning performance.It can achieve the±70°scanning in the E-plane.The maximum gain drop is kept within 3 dB and the side-lobe level is less than-11 dB when the scanning range reaches to±70°.At the same time,the profile is only 0.22???is the air wavelength at 3GHz?.In the fifth chapter,a 5×5 planar array is designed by using the antenna element proposed in Chapter 3,verifying that the tightly coupled array proposed in this thesis has the characteristics of broadband,wide-angle scanning and low profile.The electromagnetic simulation shows that the proposed array can achieve two-dimensional scanning,and has good scanning performance in both the E-and H-planes.When the gain decreases within 3 dB and the side-lobe level is less-10 dB,the 5×5 array can achieve±60°scanning in the E-plane and±50°scanning in the H-plane.Chapter 6 summarizes the work of this thesis.The shortcoming of the present work,the direction of the next work and the development trend of the tightly coupled phased array antenna technology are discussed.