Study On Optimization Design Of Sparse Plannar Array Antenna

Under the requirements of same array aperture, sparse array antenna can approach to uniform array antenna with less elements of array, which is favorable for cost control; however, under the requirements of the same number of elements, sparse array antenna can have narrow main beamwidth, which is better for the enhancement of system performance. Besides, the enlargement of the element spacing can weaken the mutual coupling. At last, sparse array antenna can simplify the design of feed network. In this way the complexity of the system will be decreased. All the merit mentioned above make the sparse array antenna a better choice for practical design, especially for the case where the system require narrow main beamwidth and high antenna gain is not so extremely at the same time.The reducing of element number will enlarge the side lope level, thus it is necessary to optimize the position and the excitation of the elements of the sparse array antenna. In order to obtain the low peak side lobe level and the expected radiation pattern of the sparse array antenna, this dissertation mainly study the optimization design of the number and the location of elements, amplitude and phase of the current excitation based on the given array shape. Under the constraints of fixed array aperture, the number of elements and the minimum element spacing, this article study a method of dimensionality reduction. At last, the matrix pencil method is applied to sparse planar array with smaller number of element for better performance. The main points and innovation points are described as follows:1. The basic concept of array antenna is introduced, the computation formula of pattern functions of array antenna is deduced, and the optimization design model of sparse array antenna is put forward.2. The dimensionality reduction method based on genetic algorithm under the multirestrictions is studied, which is used to optimize the concentric nine ring sparse array. This method improves the insufficient of the element distribution optimization in the concentric ring array. In this way co-optimization number and location of the elements on the ring can be achieved, which can reduce the complexity of the optimization method for planar array.3. The matrix pencil method is applied to the optimization design of the sparse lineararray and sparse planar array. The approximation of the desired pattern within a given tolerance is achieved by performing low rank approximation of the pattern samples matrix, which is used to calculate the number of elements and reconstruct the excitation and position. This method is a non-iterative synthesis method which can guarantee the global optimization and improve the computational efficiency.4. The extended matrix pencil method and extended forward-backward matrix pencil method based on matrix pencil method are studied, which is used to optimize the multiple patterns of sparse linear array and sparse separable planar array with smaller number of element. The simulation results show that these two methods can realize the optimization of the multiple pattern of non-uniform array antenna.