Study On The Fast Calculation And Optimization Of Ultra-Wideband Low Sidelobe Array Antenna Pattern

The UWB antennas and array have been widely used in radar system, wireless communication, medical diagnosis and so on. Antenna array attracts more and more concern and attention as it has advantages of high gain, flexible and adjustable beam, low side lobe level and high resolution. For the large-scale finite antenna array, it is a difficult problem to calculate and optimize the radiation pattern accurately and efficiently, especially the research on time-domain radiation pattern has not been mature enough. Therefore, in consideration of the mutual coupling, fast calculating and optimizing the time-domain radiation pattern of the UWB large-scale antenna array has been of great importance.In this paper, the AEP is used to consider mutual coupling between array elements, the small array extrapolation method is applied to improve the calculation efficiency of the large-scale antenna array, and Taguchi algorithm is combined to realize the optimization of time-domain radiation pattern. The main research work is as follows:Firstly, based on the time-domain radiation principle, this paper studies the design method and radiation characteristics of the UWB antennas and array. In order to miniaturize the size of antenna, a Vivaldi antenna with slot is proposed, working at the frequency segment of 2.96-11 GHz. The knife type TEM horn antenna array is applied to analyze mutual coupling between the array elements and the basic properties of time-domain radiation pattern, and the time-domain beam scanning in three-dimensional space is realized by controlling the time delay. Then the Vivaldi dual-polarized antenna array is designed to study the radiation performance in frequency and time domain.Secondly, the AEP and the small array extrapolation method are studied to fast calculate time-domain radiation pattern of the large-scale array. The method is applied to calculate the time-domain radiation pattern of large-scale linear array, triangular-grid planar array and dual-polarized planar array, and the calculation results are in good agreement with that simulated by software, the cost time is obviously decreased at the same time, so the accuracy and efficiency of the method are verified. Furthermore, a simplified method is proposed by formula derivation. With this method, the calculation problems of a large-scale array can be transformed into that of several small arrays, which avoids the complicated operation when exacting the AEPs of subarray, the calculation efficiency is improved greatly.Finally, Taguchi algorithm is applied to optimize the time-domain radiation pattern of the antenna array. For an antenna array, main lobe width is in contradiction with side lobe level, in order to optimize one objective when the other one is not deteriorated seriously, this paper studies the problem of multi-objective optimization. The optimization goals are taken into account at the same time by adding weighting coefficients, which are adjusted to achieve the Pareto optimal solution to satisfy the requirement. The results of calculation examples show that low side lobe level is achieved while main lobe width is limited. This method is demonstrated as well, and it can provide a reference for the application of actual engineering.