Research On The Characteristics Of Wide-Angle Scanning Antenna Arrays

Phased array antenna have a wide range of applications in radar and communications due to its unique beam steering characteristics and fast scanning characteristics.With the rapid development of wireless communication,the phased array antenna has gradually developed towards broadband and wide-angle scanning.In this thesis,the wide-angle scanning characteristics of phased array antennas are studied.1.Research on wide-angle scanning antenna array based on wide beam antenna.(a)Design of wide beam antenna.In order to satisfy the beamwidth characteristics of wide-angle scanning arrays for antenna elements,the wide-beam magneto-electric dipole antenna is used as element to study wide-angle scanning of the array.The antenna adopts a horizontally butterfly dipole as an electric dipole,a vertically half ring is used as a magnetic dipole,and the broadband impedance matching of the antenna is realized by using the microstrip-tostripline transition balun.The designed antenna has an impedance bandwidth of 2.71-4.03GHz(VSWR<2)and a relative bandwidth of 39%.In the entire operating frequency band,the widest 3d B beamwidth of E-plane and H-plane are 120° and 113° respectively.To vertify the feasibility of the antenna for wide-angle scanning array,the antenna is fabricated and measured.In addition,two orthogonal polarized elements are used to form a dual-linear polarized antenna.The measured results show that the dual-linear polarization antenna have wide bandwidth and wide beam characteristics.(b)Design of 8-element arrays and feeding network.In order to study the scanning characteristics of the array,a single-linear polarized magneto-electric dipole is used as the element,and an 8-element uniformly distributed linear arrays with a distance of 43mm(0.43?low-0.57?high)is designed,and a metal plate is introduced between the elements to reduce the mutual coupling between adjacent elements.The simulation results show that the introduction of the metal plate can effectively improve the active VSWR of the array element compared with no metal plate.On this basis,a power divider with equal amplitude and phase,a power divider with equal amplitude and fixed scan angle are designed as the feed network of the array.The simulation results show that the array with 0° scanning satisfies VSWR < 2 in 3.4-4 GHz frequency band,and the array with fixed scan angle satisfies VSWR < 2 in 3.3-4 GHz frequency band,the array achieves a 58° scan angle at 3.3GHz and 45° scan angle at 4GHz.2.Research on wide-angle scanning antenna array based on tightly coupled technology.(a)Design of dual-linear polarized tightly coupled antenna.In order to make the antenna array satisfy the characteristics of low profile,ultra-wideband and wide-angle scanning,tightly coupled dipole is used as array element.In the design of element,the coupling capacitance is introduced by overlapping the dipole ends to broaden the antenna bandwidth,and the wide-angle scanning is realized by using the periodic printed metal instead of the traditional dielectric matching layer,meanwhile,two dipole antennas are orthogonally placed to product dual-linear polarized antenna.The design achieves superior performance of 6.4:1 bandwidth(2.52-18.85GHz)at broadside with VSWR < 3.Meanwhile,The design achieves 4.8:1 bandwidth(3.56-17.05GHz)and 3.5:1 bandwidth(5.79-20GHz)when scanning ±65° in E-plane and H-plane.(b)Design of improved dual-linear polarized tightly coupled antenna.The resistive frequency selective surface(RFSS)is used to suppress the impedance mismatch occurring at the high frequency while scanning in the E-plane,it can further expand the bandwidth of antenna.The design achieves superior performance of 7.6:1 bandwidth(2.52-19.27GHz)at broadside with VSWR < 3.Meanwhile,The design achieves at least 6.6:1 bandwidth(3-19.2GHz)while scanning ±65° in E-plane and H-plane.(c)Research on tightly coupled dipole array.Before studying the finite array,the short circuit truncation method is applied to truncate tightly coupled semi-infinite periodic array edge elements,then the simulation of tightly coupled phased array(8×8)is completed,and the matching characteristics and scanning characteristics of each element in the array are analyzed.