Study On Key Technologies Of Wide-angle Scanning Phased Array Antenna

With the development of modern wireless communication technology,the application of phased array antennas has become more and more extensive.Compared with a single antenna,it has the can realize high gain,beamforming,beam scanning,etc.By amplitude modulation of the elements,it can also realize low sidelobes.A wide range of application scenarios also put forward new requirements for the performance of phased array antennas.For example,the field of military radar requires phased array antennas with broadband so that an antenna can achieve multiple functions;the field of satellite communications requires phased array antennas with wide-angle scanning capability to increase the number of visible satellites.In order to meet those requirements and challenges,this thesis take the tightly coupled array as the research.Moreover,this thesis proposes to use the tri-polarized antenna technology in the wide-angle scanning phased array antenna.The main content of this thesis is summarized as follows:1.A wide-angle scanning phased array antenna applied to Ku-band satellite terminal is proposed in this thesis.By utilizing the mutual coupling,this array antenna can realize a wide work bandwidth.A wide-angel impedance matching(WAIM)layer is deigned on this basis.On the condition of infinite array,over 42.5% bandwidth and ±70°scanning range can realize VSWR<3,and the profile is only 0.18λ(λ is the working wavelength of intermediate frequency).A 4×4 planar array was constructed based on this element,and the gain fluctuation is less than 3d B when it scan to ±70°.2.It is proposed to apply the tri-polarized antenna technology to the wide-angle scanning phased array antenna.By taking the three orthogonal dipole antennas as an example,an ideal omnidirectional tri-polarization antenna model is constructed.By amplitude modulation of the tri-polarized elements,a beam pointing to any direction in space can be obtained.Therefore,all scanning angle is the normal direction of the antenna element,which can ensure that the polarization purity will not decrease with the increase of scanning angle.Moreover,the gain of a linear array with array distance of 1/2λ does not decrease with the increase of the scanning angle.3.Taking two kinds of antennas(microstrip-monopole and long slot-monopole)as examples to simulate and analyze the tri-polarized antenna’s performance of wide scan.The linear array of microstrip-monopole can scan to ±60° with gain fluctuation less than 1d B and XPD more than 20 d B.The 4×4 planar array of long slot-monopole can scan to ±70°with gain fluctuation less than 2d B and gain fluctuation less than 3d B in the direction of endfire.Through simulation and analysis,it is verified that it is feasible to improve the performance of wide-angle scanning phased array antenna by using tri-polarized antenna.