Effect Of Structural Deformation On Microstrip Antenna And Its Application

The electrical performance of microstrip patch antennas(MPA)are very sensitive to the size of the structure,and its structure and electromagnetic coupling characteristics exist.In the process of MPA manufacturing,small deviations in dimensions often cause changes in effective electrical dimensions.There are also inhomogeneities in the dielectric substrate,these will cause deviations in the electrical performance of the antenna.In addition,during the service of the antenna,structural deformation caused by external load will also cause the antenna's electrical performance to decrease.In order to analyze the influence of structural deformation on the electrical performance of the antenna,the following studies were performed:First of all,for the special object of air microstrip antenna(AMA),the effect of ground plane deformation(GPD)on its electrical performance was studied.By using cosine function to describe several typical forms of GPD.Based on this,different GPD sizes and distributions can be obtained by changing parameters such as the amplitude and period of the function.By introducing the average thickness of the air medium into the calculation model,the relationship between AMA resonant frequency offset and GPD amplitude was established.Simulation results show that there is a strong linear relationship between the offset of the resonant frequency and the amplitude of the deformation.The directivity also decreases with the increase of the deformation amplitude.This mathematical model can be used to predict the effect of GPD on the electrical performance of AMA.Then,for the dielectric MPA,based on the cavity theory,a mathematical model for the effect of the overall deformation of the antenna structure on the resonant frequency offset is established.By starting from the three-dimensional finite element model of the antenna structure,coupling the mechanical analysis unit model with the electromagnetic analysis unit model,a structural/electromagnetic coupling analysis method for analyzing MPA is proposed.Therefore,the structure and the electromagnetic analysis use the same grid,it can accurately analyze the electrical performance of the deformed antenna and improve the accuracy of the electromechanical coupling analysis.The case analysis results show that deformation of the overall antenna structure will cause resonant frequency and main beam pointing shift,increased beam width and reduced directivity.Finally,the above-mentioned influence mechanism models of AMA and MPA were applied to structural strain detection.According to the transmission-line theory,the influence of the structure strain on the antenna resonant frequency is further analyzed,and the quantitative relationship between the resonant frequency offset and the structure strain is established.By analyzing theS₁₁ of the antenna,the antenna resonant frequency is obtained,and then the stress and strain information of the structure to be obtained.Simulation results show that the method is effective.