| Microwave antennas,typically represented by reflector antennas and phased array antennas,are widely used and play an important role in radio astronomy,antenna detection and other fields.Single-aperture reflector antenna has strong signal collection capability,high signalto-noise ratio,and can effectively collect weak signals,which makes it indispensable in the field of radio astronomy,and it’s simple and easy-to-use structure also makes it occupy a position in the field of antenna detection in the early days.With the requirements of high gain,narrow beam and low sub-flap,phased array antenna has gradually increased its position in the field of antenna detection because of its flexible and shortcut beam,fast scanning speed and good anti-interference ability.The status of phased array antennas in the field of detection is gradually rising.Due to the improvement of the performance of pointing accuracy and detection range,both reflector antenna and phased array antenna are developing in the direction of high gain in high frequency band.The influence of structural factors such as feed,main surface accuracy,array element position or electromagnetic factors such as excitation current amplitude and phase on the performance is more prominent.The relationship between structure and electromagnetic and performance is getting closer and closer,and the electrical performance of microwave antenna such as gain and pointing is curbed by structure and electromagnetic uncertainty is more and more obvious.How to analyze the impact of uncertainty,to protect the antenna performance is important.To this end,this paper,taking reflecting surface antenna and phased array antenna as the objects,focuses on the evolution mechanism and guarantee method of microwave antenna electrical performance under structural and electromagnetic uncertainties,and carries out the following five aspects of research.1.The interval analysis method is used to study the uncertainty factor in microwave antennas for its characteristic of easy access to upper and lower bounds.To this end,the properties of the subordinate distribution rate of interval numbers,the inclusion preserving order of structural and electromagnetic interval number operations,the interval expansion process of pattern functions and the excess width of interval value functions are derived and proved in detail.Based on the order-preserving nature of the Lipschitz interval expansion,an interval refinement method is proposed to improve the amplification effect in the interval calculation process,which lays a theoretical foundation for the subsequent development and application of the uncertainty coupling model for microwave antennas.2.The electromechanical coupling model of reflecting surface antenna structure uncertainty is established,and the mechanism of the influence of the structure uncertainty on the electrical performance is revealed by using the model.The amount of phase interval of the aperture surface caused by the deviation of the feed source position is deduced.The influence of the feed source pointing uncertainty on the amplitude of the aperture surface is analyzed.The expression of the directional diagram under the uncertainty of the main reflecting surface shape surface is given,and the formula of the upper and lower exact boundary of the directional diagram of the reflecting surface antenna under the influence of the structural uncertainty is determined.Finally,the correctness of the interval coupling model is verified by the simulation example of 110 m antenna model,and the influence mechanism of feed source and main reflecting surface uncertainty on antenna gain,sidelobe,pointing and other performance is discussed.3.The method of guaranteeing the performance of reflecting surface antenna shape surface under uncertainty factors is proposed.The installation scheme of the edge sensor is determined.The main surface is partitioned according to the main beam structure of the reflective surface antenna,and the cumulative error caused by the measurement uncertainty of the sensor is reduced by the method that each area panel calculation is performed independently.The panel attitude calculation process under the influence of the measurement uncertainty is derived to complete the efficient calculation of the antenna panel attitude.The optimal working surface fitting method based on least squares method and node quadratic sampling method is proposed to improve the accuracy of reflective surface fitting.Then the adjustment amount of active surface actuator is calculated.Finally,the accuracy of the proposed method is verified by the simulation case of 110 m antenna in Qitai and the project case of 26 m Nanshan Radio Telescope.4.An electromechanical coupling model of active phased array antenna structure and electromagnetic uncertainty is built.Firstly,on the basis of the ideal field strength directional map function of the active phased array antenna,the influence of the uncertainty of the array element spatial position is analyzed,the directional map of the array element pointing rotation error is calculated,and the analytical model under the phase uncertainty of the excitation current amplitude is deduced.Then the interval phase calculation expressions under the deviation of array element position are derived for three common array element layout forms,namely linear array,rectangular grid array and triangular grid array,and the power direction diagram calculation under the structural electromagnetic uncertainty is completed.The given solution method is used to realize the analysis of the electrical performance under the uncertainty of array element position and excitation current amplitude phase,and the specific requirements for the antenna to ensure the performance in practical applications are discussed based on the results.5.The study of robust regulation technology of active phased array antenna performance oriented to antenna detection capability is realized.Aiming at the capability analysis and compensation problem of active phased array antenna with antenna detection as a function,the deviation analysis of antenna gain,sidelobe level and half power angle on the farthest detection distance is completed.The interval amount calculation formula of distance and angle detection accuracy is determined.The influence of beam width on target resolution is analyzed,and the interval expression of antenna main capability index is given,so as to realize the fast prediction of detection performance.Then an active phased array antenna performance guarantee method based on interval refinement is proposed,which improves the amplification effect of the compensation amount interval in the calculation process.Finally,the validity of the computational model is verified by an example,and the results show that the proposed method can effectively reduce the interval width of the amplitude phase compensation amount of the excitation current and improve the detection capability and stability of the antenna. |
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