Research And Analysis Of Wideband And Wide Angle Scanning Antenna Array

With the rapid development of modern military equipment,the requirements for radar systems are also increasing.Large-bandwidth,large-scan angle phased-array radars are increasingly becoming an important direction for the development of radar systems.As an important part of the phased array radar,the phased array antenna also requires its wideband and wide-angle scanning characteristics.The tightly coupled array antenna utilizes the mutual coupling effect between the elements to widen the bandwidth and has good scanning performance at the same time,which is a research hotspot of the phased array antenna in recent years.This paper mainly studies and analyzes the tightly coupled phased array with wide bandwidth and wide scanning angles.The main research contents are as follows:(1)Two asymmetric dipole antenna elements for tightly coupled arrays are proposed.Firstly,a strong coupling capacitance is generated by a close interdigitated coupling structure between adjacent elements to cancel out the inductance effect caused by the reflective ground and realize the wideband characteristics of the tightly coupled antenna.Secondly,a low-profile gradient microstrip balun is designed for the dipole structure,which realizes the conversion from an unbalanced feed structure to a balanced feed structure,and uses a graded structure to achieve impedance matching.Finally,the bandwidth of the antenna is further widened by loading a wide-angle matching layer and a resistive frequency-selective surface.The results show that the “tree-branch”-like element can provide an impedance bandwidth of 7:1(2-14GHz)and a scanning angle of ±75° in E plane and ±45° in H plane.The “ring”-like element is loaded with two resistive frequency selective surfaces,which improves the impedance characteristics of the antenna in H plane and further reduces the VSWR of the antenna during scanning,it can provide an impedance bandwidth of 7:1(2-14GHz)and a scanning angle of ±75° in E plane and ±45° in H plane.(2)Using the two types of element to form arrays.Firstly,the semi-infinite period array is studied and analyzed.The method of loading resistive loads on the edge of the array is used to effectively improve the edge truncation effect of the finite array.Secondly,on this basis,an 8×8 finite array was designed.The simulation verified the good impedance bandwidth and scanning performance of the tightly-coupled array antenna.Several methods to realize the low sidelobe of the array antenna pattern were studied.The array gets a lower sidelobe level.Finally,a broadband feed network was designed for the“tree-branch”-like array,and the entire array structure was perfected.The array can provide an impedance bandwidth of 7:1(2-14GHz)and a scanning angle of ±75° in E plane and ±60° in H plane.