Simulation Study Of A L-band Dual Circularly Polarized Hexagonal Phased Array

Phased array antenna(PAA)mainly realizes beam scanning by controlling the phase of the excitation coefficient.It has flexible beam scanning characteristics and can realize multitarget search,tracking,recognition and other functions.It is widely used in radar,mobile communication and other fields.Circular polarization(CP)PAA is mainly used in satellite communication system.Wide angle scanning has become a research hotspot.The circular microstrip patch has many advantages,such as good processing consistency,symmetrical radiation pattern,low cross polarization and wide axial-ratio-beam width(ARBW).Because of the influence of array mutual coupling on the excitation coefficient,the radiation pattern of the array deviates from the expected pattern.In this paper,the hexagonal(cluster)PAA with bicyclic polarization is studied.The main works are as follows:Firstly,the research background and significance are introduced,the application of L-band in satellite communication is summarized,the characteristics of circularly polarized antenna are described,and the research status at home and abroad is given.Based on the cavity mode theory of microstrip antenna,the main mode pattern of singlelayer circular microstrip antenna is calculated.Based on the pattern multiplication,the electric-field intensity pattern of hexagonal PAA is calculated.The microwave multi-port network is used to describe the mutual coupling of antennas,and the calculation formula of active voltage standing wave ratio(VSWR)is given.Single-layer circularly polarized circular microstrip patch antenna(SLCMSPA)and doublelayer circularly polarized circular microstrip patch antenna(DLCMSPA)are simulated.The impedance bandwidth of SLCMSPA is 20 MHz,the directional coefficient is 7.46 d B,the half-power beam width(HPBW)is 87 degrees,and the axial-ratio beam width(ARBW)is 119 degrees.DLCMSPA is a coupled patch based on SLCMSPA antenna.Its impedance bandwidth is 62 MHz,directional coefficient is 8.77 d B,HPBW is 76 degrees and ARBW is 148 degrees.The two-stage branch line coupler(BLC)is simulated as the feed network of the antenna to realize left-handed circular polarization(LHCP)and right-handed circular polarization(RHCP).Using the method of rotating array elements,based on SLCMSPA element,the relationship between port S parameter and rotation angle of the element in binary array with unit distance(d)of 0.5 wavelength(lambda 0)is simulated to determine the orientation of the element and the cluster seven-element array with the best orientation of the element.Aiming at SLCMSPA-PAA with 7 and 19 elements,the simulation model of antenna is established.The impedance matrix,scanning active VSWR,scanning gain pattern,AR and other electrical parameters of the array are obtained.Compared with the theoretical calculation results of MATLAB,the influence of mutual coupling on the radiation characteristics of the array is analyzed.The scanning capability of the antenna under different d conditions is studied.The simulation results show that the antenna has approximately the best performance when d is 0.7 wavelength in vacuum.The maximum angle scanning angle of the 7-element array is 53 degrees and the gain is 9.59 d Bic,which is 6.2 d B lower than that without scanning.The maximum angle scanning angle of the 19-element array is 63 degrees and the gain is 12.43 d Bic,which is 7.53 d B lower than that without scanning.The DLCMSPA-PAA with 7 and 19 elements is simulated.The simulation results show that the antenna has approximately the best performance when d is 0.7 wavelength in vacuum.The maximum angle scanning angle of the 7-element array is 49 degrees and the gain is 10.34 d Bic,which is 5.61 d B lower than that without scanning.The maximum angle scanning angle of the 19-element array is 60 degrees and the gain is 12.70 d Bic,which is 7.31 d B lower than that without scanning.