The Optimal Subarray Partitioning And Processing For Array Radars

For large-scale array radars, the subarray technique, which can reduce the system complexity and cost remarkably, attracts great attention in the field of radars, and is widely employed in the advanced radar systems, such as GBR, THAAD and AEGIS. However,the choice of subarray layout has a significant impact on the performance of radar systems.Currently, it is a great challenge to realize the optimal subarray partition and develop the corresponding signal processing with the current level of technology. In addition,the subarray technique is the bottleneck of some current developing array radars of our country. Researches about the optimal subarray partition and the signal processing have been developed in this dissertation. The main contributions of the dissertation are as follows:1. The basis of the subarray tecnique. Embarking from the subarray technique’s concept and applications, this dissertation shows the mathematical model of the subarray technique, and reveals the mechanisms of the effects of the subarray technique on the performance of antenna pattern. Using the “lattice theory”, the beamforming principles of the subarrayed antennas are presented. Beamforming methods with the arbitrary subarray configurations are established, which have formulated a uniform theoretical framework including the Limited Field of View(LFOV), Wide-band and Wide-angle Scanning(WBWS) as well as the Multiple Simultaneous Beamforming(MSB) techniques.2. The irregular subarray technique. The innovative irregular subarray architecture named ployformed subarray is proposed for arrays with elements arranged at an arbitrary lattice. The high-performance antenna pattern with low grating lobes can be obtained using such irregular subarray, meanwhile, the implementation is very engineering friendly. Based on the exact cover theory, the exact partition and quasi-exact partition are proposed to solve the exact partition of the array antennas with the given irregular-shaped subarrays. At last, considering the polarization characteristics of array element and the engineering practicability, the improved partitioning on the basis of the quantitative analysis with the innovative irregular subarrays is given.3. The overlapped subarray technique. The pattern calculation methods of the array antennas with one-dimension and two-dimension overlapped subarrays are deduced.Employing the alternate optimization strategy, a weighting optimization method of the overlapped-subarrayed antennas is proposed. Using the proposed method, the complex non-convex optimization problem has been transformed into two linear programming problems which can be solved in little iteration. And, most importantly, the new method obtained the better performance pattern compared with the traditional methods, such as the two-stage low sidelobe weighting method. The influence of the weighting errors on the antenna pattern, coming from the subarray level and element level, has been illustrated via the theory analyzing and numerical simulation.4. The subarray technique in the monopulse application. Based on the monopulse frameworks of array antennas, the synthesis methods of the sum/difference pattern at the subarray level are obtained. The excitation matching principle has been used to optimize the subarray configuration. Some previously unrecognized connections between the clustering theory and the subarray-configuration optimization are investigated, then,the subarray partitioning method based on the clustering algorithm is proposed, which can improve the performance of the monopulse, adjust the subarray number flexibly and decrease the sidlobe level further. At last, the signal processing method of the subarrayed monopulse is investigated, the performance of the generalized monopulse principle is deduced, and the corresponding numerical results are given.5. The subarray technique in the adaptive array processing. The evolution and the differences of the subarray techniques which are used in the SLC, ADBF and STAP techniques have been analyzed. Next, this research focuses on the subarrayed SLC technique and the subarrayed STAP technique. For the subarrayed SLC technique, the main/auxiliary channels designing method based on the exact cover theory in the SLC application is proposed, which can obtain the better interference suppression. For the subarrayed STAP technique, the optimal partitioning method based on the ant colony optimization theory is proposed, which owns the better clutter rejection performance.