Study On Wide-Angle Scanning Phased Array Antenna

With the rapid development of modern radio systems and the ever-increasing demand of human beings,phased array antenna has been widely used in the defense military fields and many civilian fields,such as radar,satellite communications,astronomical meteorology,air traffic,earth exploration,space exploration,remote sensing mapping,driverless,5G communication,biomedical,and so on.The multi-domain requirements of phased array antenna has led to higher performance requirements for phased array antenna,such as versatility,low cost,and fast flexibility,especially for wider functional coverage of the scanning beam.Therefore,the wide-angle scanning characteristics of phased array antenna have become a hot topic and key topic for scholars at home and abroad.For the key problems how to improve the perforamce of wide-angle scanning of phased array antenna need to be solved,the proposed doctoral dissertation has carried out a more comprehensive theoretical research,method research,experimental research and applied basic research.Based on the classical aperture current distribution theory,the proposed doctoral dissertation introduces a new perspective which is stereoscopic control of the aperture current.The proposed doctoral dissertation proposes a novel method which is a simple and reasonable to broaden the beamwidth of the antenna.Secondly,based on the principle of aperture current distribution,two reconfigurable antennas are designed.These antennas provide a new idea for studying the wide-angle scanning performance of phased array antenna,and provide a new development direction for satisfying multilfunction.According to the wide beam method proposed in the proposed dissertation,two kinds of wide beam antenna units are designed.Two linear array antennas are designed so that the wide-angle scanning perforance in the H-plane and E-plane linear array can be greatly improved.Besides,based on the method to improve the wide beam of the antenna,combined with active mutual coupling analysis,a planar wide-angle scanning phased array antenna with excellent performance is designed.Finally,from the design of the wide angle impedance matching and periodic structures,the proposed dissertation designs a dielectric-metal hybrid periodic structure to replace the ground plane of the phased array antenna.This method could improve the wide-angle scanning performance of the phased array antenna.The main work and innovations of the proposed dissertation are summarized as follows:(1)A novel method for improving the radiation performance of an antenna is proposed.With a simple vertical coupling structure to lead to realize three-dimensionally distribution of the aperture current distribution of the antenna,the radiation characteristics of the antenna are improved and the antenna can radiate a wide beam radiation pattern.(a)According to the wide beam method,by adding a pair of metal walls between the sides of the traditional microstrip antenna,the radiation aperture current distribution is changed,and a wide beam microstrip antenna is designed.The 3dB beam width of the wide beam antenna in the proposed dissertation in the E-plane is twice that of a traditional microstrip antenna.And the 3dB beam width in the H-plane is also significantly improved.(b)By deforming the arm of the conventional magnetoelectric dipole antenna,the aperture current distribution of the magnetoelectric dipole antenna is changed,and the beam width of the magnetoelectric dipole antenna is broadened.By adding the metal columns,a three-dimensional aperture current distribution with excellent performance is realized in a relatively wide frequency band.Hence,a wide-band beam magnetoelectric dipole antenna is designed.The designed antenna can realize wide beamwidth radiation patterns of H-plane and E-plane in the operating frequency range of 3.3 GHz to 7.8 GHz(81.1%),where in the beam width in the E-plane is wider than the beam width in the H-plane.At 5.5 GHz,for instance,the antenna has the widest beamwidth,whose the half-power beamwidth angle in the H-plane is 186°,and in the E-plane is 215°,respectively.At 7.5 GHz,the beamwidth of the antenna is the narrowest,whose the half-power beamwidth angle of the H-plane is 83°,and in the E-plane is 106°,respectively.(2)Combining the wide beam method with the controllable PIN switch diodes,a flexible and controllable method for the antenna aperture current distribution is proposed to achieve flexible control of the antenna radiation performance.(a)Design a new type of patternl reconfigurable antenna.The proposed antenna can not only achieve the switching of the radiation pattern in five directions,but also realize the reconfigurable beamwidth of the radiation pattern.(b)Design a new type of pattern and polarized reconfigurable antenna.The proposed antenna can not only realize all the reconfigurable modes like the antenna in(a),but also realize to switch among linear polarization,left-hand circular polarization and right-hand circular polarization.Especially,the circularly polarized radiation pattern has the perforamce of a wide beam width and wide axial ratio beamwidth.(3)Based on the method to improve the beamwidth of the antenna,two wide-angle scanning phased linear array antennas are designed and tested.(a)A wide-angle scanning linear array antenna based on a wide beam U-slot microstrip antenna is designed.The H-plane linear array antenna can scan the beam from the end-fire direction to the broadside direction in the operating frequency band with the scanning beam gain fluctuation less than 3dB.The E-plane linear array antenna can scan the beam from-75° to +75° with the beam gain fluctuation less than 3 dB in the operating frequency band.(b)A wide-angle scanning linear array antenna with a slot-coupled feed antenna element is designed.This kind of antenna not only broadens its radiation beamwidth,but also adds a dielectric plate to its feed gap.The proposed method can achieve the same function with the Wheeler' method adding a dielectric sheet above the array antenna.However,they are different.The function can not only improve the impedance matching of the antenna,but also reduce the size of the antenna structure.The beam in the H-plane linear array antenna in the whole operating frequency band can scan from-70° to +70° with the beam gain fluctuation less than 3dB.The beam in the E-plane linear array antenna in the whole operating frequency band can scan from broadside direction to the end-fire direction with the scanning beam gain fluctuation less than 3dB.(4)Inspired by Wheeler's addition of a dielectric sheet above the antenna and combined with the periodic structure method,the method of adding a high-impedance periodic structure under the traditional antenna is proposed to improve the wide-angle scanning impedance perforamce the radiation performance of the antenna.The beam of the antenna can scan to ±60° with the scanning beam gain fluctuation less than 3.5 dB.The side lobe of the scanning beam is low and the half power beam angle of the scanning beam is narrow.(5)The wide-angle scanning array antenna is designed based on magnetoelectric dipole antenna.The array antenna has the characteristics of miniaturization,low cost,simple structure and light weight.Besdies the proposed antenna has extremely high engineering application value.(a)Based on the wide-beam magnetoelectric dipole antenna,an H-plane wide-angle scanning linear array antenna is designed to achieve the wide-angle scanning performance which is the beam scanning from-60° to +60° with the gain fluctuation less than 3dB.(b)An E-plane wide-angle scanning linear array antenna is designed,which can also realize the wide-angle scanning performance which is the beam scanning from-60°to +60° with the scanning gain fluctuation less than 3dB and the low side lobes.(c)Based on the wide beam magnetoelectric dipole antenna,a simple 8×8 planar wide-angle scanning phased array antenna is designed,which can be realized the wide-angle scanning performance which is the beam scanning from-60° to 60° in the entire two-dimensional plane with the scanning beam gain fluctuation less than 3 dB and the relatively low sidelobe,especially the very low sidelobe in the diagonal plane.In addition,the active reflection parameters of the antenna are less than-10 dB in its whole operating frequency band.