Research On Polarization Characteristics Of Conformal Microstrip Antenna Array Based On Error Theory

The fields of modern electronic reconnaissance,electronic countermeasures and remote sensing have put higher and higher requirements on the purity of electromagnetic wave polarization information acquisition.The accurate characterization and analysis of the polarization law is of great significance for improving the purity of the transmitting and receiving antennas and less the interference of parasitic polarization.However,the antenna will introduce various types of errors during processing,installation,and service,which seriously deteriorates the antenna's polarization performance.This paper analyzes the sources of errors in the manufacturing,installation,and service of conformal microstrip antennas,and divides the errors at multiple scales.Using the tightly packed snowball model,a small-scale error model including the surface roughness of the copper foil is established,and the effect of small-scale errors on the polarization performance of the microstrip antenna is analyzed using multimode theory.Aiming at the influence of the shape of the carrier on the antenna during installation and service,the mesoscale error model of the unit under different curvature and the large scale error model of the array are established to analyze the influence of the medium and large scale on the polarization of the conformal antenna array.Finally,the small,medium and large scale errors are integrated to analyze the effect of multi-scale errors on the polarization performance of the antenna,and to explore the effect of different scale errors.This analysis method provides guidance for the subsequent antenna design,essentially reduces the probability of parasitic polarization and improves the polarization purity.The small-scale error is a random error generated during the antenna manufacturing process,including the roughness error of the copper foil surface,the line width accuracy error of the patch,and the thickness tolerance of the dielectric substrate.In the modeling of surface roughness,periodic function surfaces,Gaussian surfaces,hemispherical surfaces,and tightly packed snowball surfaces are used as equivalent rough surfaces.Finally,tightly packed snowball surfaces with high accuracy and fast calculation are selected.The rough electromagnetic boundary is solved by wave equation.The internal field of the microstrip antenna and the magnetic flux distribution on the side is analyzed,the radiation pattern of the microstrip antenna with rough surface is characterized by multimode theory,and a smallscale error model is established.The medium-scale error is that during the installation of the antenna,due to the irregular shape of the carrier,the antenna undergoes different degrees of warpage and deformation,which in turn causes the antenna's radiation performance to deviate from the design value.Consider that during the installation of the antenna,the patch will bend with the carrier to varying degrees.According to the shape error of the carrier,the deformation amount of the antenna is solved,the structural parameters are corrected,and then the electrical performance loss caused by the installation error is compensated.The large-scale error is the array element position shift and pointing deflection error caused by the carrier deformation during antenna service.By analyzing the position offset,the coordinate rotation transformation correction unit is pointed,and the influence of the error is introduced into the amplitude and phase of the pattern,thereby establishing a large-scale error model.Integrating different scale errors,a multi-scale error electromechanical coupling model is established to analyze the effect of multi-scale errors on the polarization of conformal microstrip array antennas.Finally,taking 2X4 conformal microstrip array antenna as the research object,the effects of various scale errors on the polarization performance of the antenna are analyzed.The simulation results are compared with theoretical calculations to verify the accuracy of the multi-scale error electromechanical coupling model in analyzing antenna polarization performance.The results show that the effects of large-scale errors and mesoscale errors are more serious,accounting for 90% of the total impact rate,and small-scale errors have less effect on the antenna polarization performance.